storage controller: fix repeated location_conf returning no shards

[jcsp]

Problem

When a location_conf request was repeated with no changes, we failed to build the list of shards in the result.

Summary of changes

Remove conditional that only generated a list of updates if something had really changed. This does some redundant database updates, but it is preferable to having a whole separate code path for no-op 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]

2754 tests run: 2630 passed, 0 failed, 124 skipped (full report)

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Flaky tests (1)

Postgres 15

• test_delete_timeline_client_hangup: debug

Code coverage* (full report)

• functions: 28.0% (6394 of 22870 functions)
• lines: 46.8% (45008 of 96116 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
93f77b7 at 2024-04-04T17:50:07.301Z :recycle:}