refactor: adopt the pulsar-admin-go library

[maxsxu]

Fixes #1024

Motivation

With the public and release of pulsar-admin-go, we can now adopt pulsar-admin-go and clean unused codes.

Modifications

This PR try best to do only below two things to avoid huge changes.

• Use github.com/streamnative/[email protected]
• Remove unused codes as they're implemented in pulsar-admin-go

Verifying this change

• Make sure that the change passes the CI checks.

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This change is a trivial rework / code cleanup without any test coverage.

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This change is already covered by existing tests, such as (please describe tests).

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This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

Documentation

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