test: fix duplicated harness name

[koivunej]

We need unique tenant harness names in case you want to inspect the results of the last failing run. We are not using any proc macros to get the test name as there is no stable way of doing that, and there will not be one in the future, so we need to fix these duplicates.

Also, clean up the duplicated tests to not mix ? and unwrap/assert.

[github-actions]

3198 tests run: 3056 passed, 0 failed, 142 skipped (full report)

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Flaky tests (2)

Postgres 15

• test_timeline_size_quota_on_startup: release

Postgres 14

• test_storage_controller_smoke: release

Code coverage* (full report)

• functions: 31.5% (6606 of 20962 functions)
• lines: 48.5% (51110 of 105431 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
ed71845 at 2024-06-11T12:59:03.544Z :recycle:}