fix(storage-scrubber): use default AWS authentication

[skyzh]

Problem

part of https://github.com/neondatabase/cloud/issues/14024
close #7665

Things running in k8s container use this authentication: https://docs.aws.amazon.com/sdkref/latest/guide/feature-container-credentials.html while we did not configure the client to use it. This pull request simply uses the default s3 client credential chain for storage scrubber. It might break compatibility with minio.

Summary of changes

• Use default AWS credential provider chain.
• Improvements for s3 errors, we now have detailed errors and correct backtrace on last trial of the operation.

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 (6)

Postgres 16

• test_subscriber_restart: release
• test_tenant_creation_fails: debug

Postgres 15

• test_change_pageserver: debug
• test_storage_controller_smoke: debug

Postgres 14

• test_pg_regress[None]: release
• test_pg_regress[4]: debug

Code coverage* (full report)

• functions: 32.6% (6938 of 21284 functions)
• lines: 50.0% (54544 of 109038 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
500a397 at 2024-07-09T16:35:31.694Z :recycle:}

[arpad-m]

I like the documenting quality of this piece of code: we see the tried methods listed explicitly. That being said, Christian has suggested precisely this over in #7667.

I think it's okay to merge it though given that with #7547 we want to remove the scrubber-specific SDK setup entirely.