Regenerate firebase client (googleapis#5821)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2020-09-02 03:47:01,540 synthtool [DEBUG] > Executing /home/kbuilder/.cache/synthtool/google-api-java-client-services/synth.py.
On branch autosynth-firebase
nothing to commit, working tree clean
2020-09-02 03:47:01,882 synthtool [DEBUG] > Cloning https://github.com/googleapis/discovery-artifact-manager.git.
DEBUG:synthtool:Cloning https://github.com/googleapis/discovery-artifact-manager.git.
2020-09-02 03:47:02,272 synthtool [DEBUG] > Cleaning output directory.
DEBUG:synthtool:Cleaning output directory.
2020-09-02 03:47:02,274 synthtool [DEBUG] > Installing dependencies.
DEBUG:synthtool:Installing dependencies.
2020-09-02 03:47:03,965 synthtool [INFO] > Generating firebaseml v1beta2.
INFO:synthtool:Generating firebaseml v1beta2.
2020-09-02 03:47:03,966 synthtool [INFO] > 	1.30.1
INFO:synthtool:	1.30.1
WARNING:root:object without properties Empty: OrderedDict([(u'properties', OrderedDict()), (u'description', u'A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); } The JSON representation for `Empty` is empty JSON object `{}`.'), (u'id', u'Empty'), (u'type', u'object')])
Writing json metadata to clients/google-api-services-firebaseml/v1beta2.metadata.json
2020-09-02 03:47:04,472 synthtool [INFO] > Generating firebasehosting v1.
INFO:synthtool:Generating firebasehosting v1.
2020-09-02 03:47:04,472 synthtool [INFO] > 	1.30.1
INFO:synthtool:	1.30.1
WARNING:root:object without properties CancelOperationRequest: OrderedDict([(u'id', u'CancelOperationRequest'), (u'properties', OrderedDict()), (u'type', u'object'), (u'description', u'The request message for Operations.CancelOperation.')])
WARNING:root:object without properties Empty: OrderedDict([(u'description', u'A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); } The JSON representation for `Empty` is empty JSON object `{}`.'), (u'type', u'object'), (u'id', u'Empty'), (u'properties', OrderedDict())])
Writing json metadata to clients/google-api-services-firebasehosting/v1.metadata.json
2020-09-02 03:47:04,885 synthtool [INFO] > Generating firebase v1beta1.
INFO:synthtool:Generating firebase v1beta1.
2020-09-02 03:47:04,885 synthtool [INFO] > 	1.30.1
INFO:synthtool:	1.30.1
WARNING:root:object without properties Empty: OrderedDict([(u'properties', OrderedDict()), (u'type', u'object'), (u'id', u'Empty'), (u'description', u'A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); } The JSON representation for `Empty` is empty JSON object `{}`.')])
WARNING:root:object without properties MessageSet: OrderedDict([(u'properties', OrderedDict()), (u'description', u"This is proto2's version of MessageSet."), (u'id', u'MessageSet'), (u'type', u'object')])
Writing json metadata to clients/google-api-services-firebase/v1beta1.metadata.json
2020-09-02 03:47:05,895 synthtool [INFO] > Generating firebasehosting v1beta1.
INFO:synthtool:Generating firebasehosting v1beta1.
2020-09-02 03:47:05,895 synthtool [INFO] > 	1.30.1
INFO:synthtool:	1.30.1
WARNING:root:object without properties Empty: OrderedDict([(u'id', u'Empty'), (u'description', u'A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); } The JSON representation for `Empty` is empty JSON object `{}`.'), (u'properties', OrderedDict()), (u'type', u'object')])
Writing json metadata to clients/google-api-services-firebasehosting/v1beta1.metadata.json
2020-09-02 03:47:07,014 synthtool [INFO] > Generating firebasedynamiclinks v1.
INFO:synthtool:Generating firebasedynamiclinks v1.
2020-09-02 03:47:07,014 synthtool [INFO] > 	1.30.1
INFO:synthtool:	1.30.1
Writing json metadata to clients/google-api-services-firebasedynamiclinks/v1.metadata.json
2020-09-02 03:47:07,677 synthtool [INFO] > Generating firebaserules v1.
INFO:synthtool:Generating firebaserules v1.
2020-09-02 03:47:07,677 synthtool [INFO] > 	1.30.1
INFO:synthtool:	1.30.1
WARNING:root:object without properties Empty: OrderedDict([(u'description', u'A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); } The JSON representation for `Empty` is empty JSON object `{}`.'), (u'properties', OrderedDict()), (u'id', u'Empty'), (u'type', u'object')])
Writing json metadata to clients/google-api-services-firebaserules/v1.metadata.json
2020-09-02 03:47:08,343 synthtool [INFO] > Generating firebaseml v1.
INFO:synthtool:Generating firebaseml v1.
2020-09-02 03:47:08,343 synthtool [INFO] > 	1.30.1
INFO:synthtool:	1.30.1
WARNING:root:object without properties CancelOperationRequest: OrderedDict([(u'properties', OrderedDict()), (u'id', u'CancelOperationRequest'), (u'type', u'object'), (u'description', u'The request message for Operations.CancelOperation.')])
WARNING:root:object without properties Empty: OrderedDict([(u'type', u'object'), (u'id', u'Empty'), (u'properties', OrderedDict()), (u'description', u'A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); } The JSON representation for `Empty` is empty JSON object `{}`.')])
Writing json metadata to clients/google-api-services-firebaseml/v1.metadata.json
2020-09-02 03:47:08,790 synthtool [DEBUG] > Wrote metadata to clients/google-api-services-firebase/synth.metadata.
DEBUG:synthtool:Wrote metadata to clients/google-api-services-firebase/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/98627463-8369-44a0-bc03-b63b09216569/targets

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Author: yoshi-automation