release-25.4: roachtest: add flaky npgsql and hibernate tests to ignore lists

[rafiss]

Backport 1/1 commits from #163783 on behalf of @rafiss.

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Add Npgsql.Tests.NotificationTests.WaitAsync_with_timeout to the npgsql ignore list and update hibernate ignore list entries for JtaTransactionJoiningTest.

These tests have been observed to be flaky in the upstream testing suites.

Resolves: #163604
Resolves: #163481

Release note: None

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Release justification:

[blathers-crl]

Thanks for opening a backport.

Before merging, please confirm that it falls into one of the following categories (select one):

• Non-production code changes OR fixes for serious issues. Non-production includes test-only changes, build system changes, etc. Serious issues are defined in the policy as correctness, stability, or security issues, data corruption/loss, significant performance regressions, breaking working and widely used functionality, or an inability to detect and debug production issues.
• Other approved changes. These changes must be gated behind a disabled-by-default feature flag unless there is a strong justification not to. Reference the approved ENGREQ ticket in the PR body (e.g., "Fixes ENGREQ-123").

Add a brief release justification to the PR description explaining your selection.

Also, confirm that the change does not break backward compatibility and complies with all aspects of the backport policy.

All backports must be reviewed by the TL and EM for the owning area.

[blathers-crl]

✅ PR #163797 is compliant with backport policy

Confidence: high
Backward compatible: true
Explanation: The pull request modifies files that are part of the non-production testing infrastructure specifically for handling flaky tests in CockroachDB's roachtest suite. The file paths pkg/cmd/roachtest/tests/hibernate_blocklist.go and pkg/cmd/roachtest/tests/npgsql_blocklist.go clearly fall under the defined non-production file patterns (listed as pkg/cmd/roachtest/). Since the changes affect only test definitions (ignore lists) and do not alter production code, they are automatically exempt from the standard requirements like addressing a critical bug or being gated behind a feature flag.

❌ ENGREQ Check Failed: Please check one of the backport category checkboxes.

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}

[cockroach-teamcity]

This change is