[ai] Use .json for unary tests instead of .txt

[rlazo]

Follow up to #6915

[github-actions]

Vertex AI Mock Responses Check ⚠️

A newer major version of the mock responses for Vertex AI unit tests is available. update_responses.sh should be updated to clone the latest version of the responses: v10.1

[google-oss-bot]

	1 Warning
⚠️	Did you forget to add a changelog entry? (Add the 'no-changelog' label to the PR to silence this warning.)

Generated by 🚫 Danger

[google-oss-bot]

Coverage Report ¹

Affected Products

No changes between base commit (7cbb80b) and merge commit (86ca716).

Test Logs

• Base (7cbb80b): https://github.com/firebase/firebase-android-sdk/actions/runs/14716955661
• Merge (86ca716): https://github.com/firebase/firebase-android-sdk/actions/runs/14723027512

1. https://storage.googleapis.com/firebase-sdk-metric-reports/Cj9e95hRxQ.html

[github-actions]

Test Results

 22 files   -  1 034   22 suites   - 1 034   14s ⏱️ - 36m 12s
 98 tests  -  5 874   98 ✅  -  5 852  0 💤  - 22  0 ❌ ±0 
196 runs   - 11 811  196 ✅  - 11 767  0 💤  - 44  0 ❌ ±0 

Results for commit e969f46. ± Comparison against base commit 7cbb80b.

This pull request removes 5874 tests.

com.google.android.datatransport.cct.CctBackendFactoryTest ‑ create_returnCCTBackend_WhenBackendNameIsCCT
com.google.android.datatransport.cct.CctDestinationTest ‑ cctDestination_shouldOnlySupportProtoAndJson
com.google.android.datatransport.cct.CctDestinationTest ‑ cctDestination_shouldSupportProtoAndJson
com.google.android.datatransport.cct.CctTransportBackendTest ‑ decorate_whenOffline_shouldProperlyPopulateNetworkInfo
com.google.android.datatransport.cct.CctTransportBackendTest ‑ decorate_whenOnline_shouldProperlyPopulateNetworkInfo
com.google.android.datatransport.cct.CctTransportBackendTest ‑ schedule_shouldAddCookieOnPseudonymousIds
com.google.android.datatransport.cct.CctTransportBackendTest ‑ schedule_shouldDropCookieOnMixedPseudonymousIds
com.google.android.datatransport.cct.CctTransportBackendTest ‑ send_CompressedResponseIsUncompressed
com.google.android.datatransport.cct.CctTransportBackendTest ‑ send_whenBackendRedirectsMoreThan5Times_shouldOnlyRedirect4Times
com.google.android.datatransport.cct.CctTransportBackendTest ‑ send_whenBackendRedirects_shouldCorrectlyFollowTheRedirectViaPost
…

♻️ This comment has been updated with latest results.

[google-oss-bot]

Size Report ¹

Affected Products

No changes between base commit (7cbb80b) and merge commit (86ca716).

Test Logs

• Base (7cbb80b): https://github.com/firebase/firebase-android-sdk/actions/runs/14716955661
• Merge (86ca716): https://github.com/firebase/firebase-android-sdk/actions/runs/14723027512

1. https://storage.googleapis.com/firebase-sdk-metric-reports/bwHwXjnpBH.html

[github-actions]

📝 PRs merging into main branch

Our main branch should always be in a releasable state. If you are working on a larger change, or if you don't want this change to see the light of the day just yet, consider using a feature branch first, and only merge into the main branch when the code complete and ready to be released.