fix(backups): configure pgBackRest stderr logging

[nanookclaw]

Summary

Adds log-level-stderr=warn to the rendered pgBackRest global configuration so the stderr logging level is configured once for every pgBackRest invocation that uses pgbackrest.conf, as requested in #1353.

The existing --log-level-console=debug backup argument is left unchanged because it controls console output for the backup action and is distinct from the stderr logging level being moved into the config file.

Verification

• python3 -m compileall -q tests/unit/test_backups.py
• ruff check tests/unit/test_backups.py
• ruff format --check tests/unit/test_backups.py
• git diff --check
• Jinja render smoke check confirmed log-level-stderr=warn appears in the rendered config

Could not run the focused pytest locally because this container lacks the project test environment: host pytest autoloads a missing evalcraft plugin, plugin-autoload-disabled pytest then lacks botocore, and poetry/tox are not installed here.

Closes #1353

[taurus-forever]

Should this

postgresql-operator/src/constants.py

Line 34 in 82b1194

PGBACKREST_LOG_LEVEL_STDERR = "--log-level-stderr=warn"

be reverted (as discussed here) ?

[nanookclaw]

I don’t think a separate constant needs to be reverted in this PR. The command-level PGBACKREST_LOG_LEVEL_STDERR approach from #1320 is not present on current main; src/constants.py#L34 is just PGBACKREST_EXECUTABLE now.

This PR applies the earlier suggestion in the config layer instead: templates/pgbackrest.conf.j2 now sets log-level-stderr=warn, so pgBackRest commands using --config=.../pgbackrest.conf pick it up without adding a per-command flag.

The only remaining command-level logging flag I see on main is _run_backup()’s --log-level-console=debug, which is backup-specific and looks intentionally preserved for backup log capture. If you want this PR to also remove or change that backup-specific flag, I can adjust it, but I kept the diff scoped to the shared pgBackRest config.

[carlcsaposs-canonical]

@taurus-forever perhaps we should set the default branch to 16/edge?

[taurus-forever]

@taurus-forever perhaps we should set the default branch to 16/edge?

It was pending stereo mode PRs release to perform massive default branch upgrade as discussed in Madrid.
It is coming ...

[marceloneppel]

LGTM!

I created #1767 to also work on 16/edge and remove the constant @taurus-forever mentioned.