feat(proxy): dont trigger error alerts for unknown topics

[conradludgate]

Problem

Before the holidays, and just before our code freeze, a change to cplane was made that started publishing the topics from #10197. This triggered our alerts and put us in a sticky situation as it was not an error, and we didn't want to silence the alert for the entire holidays, and we didn't want to release proxy 2 days in a row if it was not essential.

We fixed it eventually by rewriting the alert based on logs, but this is not a good solution.

Summary of changes

Introduces an intermediate parsing step to check the topic name first, to allow us to ignore parsing errors for any topics we do not know about.

[github-actions]

7227 tests run: 6875 passed, 0 failed, 352 skipped (full report)

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Flaky tests (2)

Postgres 15

• test_parallel_copy: release-arm64

Postgres 14

• test_physical_replication_config_mismatch_too_many_known_xids: release-arm64

Code coverage* (full report)

• functions: 31.2% (8409 of 26961 functions)
• lines: 48.0% (66776 of 139215 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
fddd23b at 2025-01-06T13:06:08.981Z :recycle:}