fix(storage-scrubber): make retry error into warnings

[skyzh]

Problem

We get many HTTP connect timeout errors from scrubber logs, and it turned out that the scrubber is retrying, and this is not an actual error. In the future, we should revisit all places where we log errors in the storage scrubber, and only error when necessary (i.e., errors that might need manual fixing)

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]

3780 tests run: 3674 passed, 0 failed, 106 skipped (full report)

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Flaky tests (1)

Postgres 14

• test_subscriber_restart: release-x86-64

Code coverage* (full report)

• functions: 32.3% (7309 of 22610 functions)
• lines: 50.4% (59104 of 117260 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
2767122 at 2024-08-27T20:22:16.529Z :recycle:}

[arpad-m]

TBH if this were in the pageserver, I'd suggest using the info log level even, as it's nothing unexpected.

[skyzh]

Well, I still prefer having a warning for whatever things go wrong even if it's self recoverable... 😛