fix(pageserver): write to both v1+v2 for aux tenant import

[skyzh]

Problem

close #8202 ref #6560

For tenant imports, we now write the aux files into both v1+v2 storage, so that the test case can pick either one for testing. Given the API is only used for testing, this looks like a safe change.

I did not test it b/c there are no existing test cases. Probably @knizhnik can help with the testing?

Summary of changes

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

3042 tests run: 2927 passed, 0 failed, 115 skipped (full report)

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Flaky tests (1)

Postgres 14

• test_subscriber_restart: release

Code coverage* (full report)

• functions: 32.6% (6936 of 21280 functions)
• lines: 50.0% (54544 of 109066 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
bee2cba at 2024-07-08T18:54:24.117Z :recycle:}