Write the migration-related settings in a fixed order

[fontaineajulien]

Fixes #1691.

needsMigrationSetting() ranged over MigrationSettingsList(), which is a map, and returned at the first false setting. Go map order is random, so the same CR produced a different settings.py from one reconcile to the next. Depending on the order, REDIRECT_TO_OBJECT_STORAGE = True was present or missing, or the two lines swapped places. Each change rewrote the <name>-server Secret and reprovisioned the pulpcore pods, and the resulting rollout triggered more reconciles, so the loop fed itself.

This PR:

• iterates over the sorted keys, using the existing sortKeys helper;
• uses continue instead of return on a false setting, so a false setting no longer hides the ones after it.

Tests: the new controllers/repo_manager/secret_test.go runs the function 100 times. On the current code both cases fail within a few runs:

• settings = "" instead of REDIRECT_TO_OBJECT_STORAGE = True;
• the two lines come out in swapped order.

With the fix, both tests pass. go test ./... passes, including the envtest suite.

[openshift-ci]

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[openshift-ci]

Hi @fontaineajulien. Thanks for your PR.

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