Patch tests for unified_analytics 5.8.8+2 fixes

[andrewkolos]

This is a follow-up to #280. Basically, that PR cherry-picked some fixes from main (unified_analytics v6) to a new branch meant to eventually be published as unified_analytics v5.8.8+2. However, since there were some API changes in v6, the tests didn't work (I already remembered to verify the tests right after I merged 😛).

This PR patches these tests. It makes LogHandler::logFile writable via a @visibleForTestingOnly setter, which I think is okay for patching an old major version.

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[andrewkolos]

The current plan is to wait and see whether @christopherfujino will be back in action tomorrow, since I don't think we really need (?) to get this published by the end of the week.

Once this merges—per https://github.com/dart-lang/tools/pull/280#issuecomment-2189866767—the next step would be to have devoncrew (or someone else with publishing permissions) publish this to pub.

[devoncarew]

Can you delete the first branches: line from https://github.com/dart-lang/tools/blob/main/.github/workflows/unified_analytics.yml#L6? I believe that will allow the tests to run for this PR.

[devoncarew]

You want the .github/workflows/unified_analytics.yml file :)

[christopherfujino]

LGTM

[andrewkolos]

@devoncarew the unified_analytics-v5.8.8+2 branch should be ready for publishing now

[devoncarew]

Published!

https://github.com/dart-lang/tools/releases/tag/unified_analytics-v5.8.8%2B2