Fix/FabAuthManager race condition on startup with multiple workers

[Pyasma]

issue : #62563
When running the API server with multiple workers, they all try to initialize FAB permissions at exactly the same time, which causes a database race condition.

This PR simply catches that IntegrityError to safely ignore it, since having multiple workers trying to add the exact same permission is actually fine. Also added 2 tests to verify this logic works.

prek checks passed

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[Pyasma]

@jason810496 @Lee-W can you please review this

[Copilot]

Pull request overview

Addresses a startup race condition when running the API server with multiple workers using FabAuthManager, where concurrent permission-role initialization can trigger DB IntegrityErrors.

Changes:

• Catch sqlalchemy.exc.IntegrityError in add_permission_to_role and suppress logging when the permission-role association already exists after rollback.
• Add _is_permission_assigned_to_role helper to verify whether the association exists in the DB.
• Add unit tests covering both the “ignore duplicate” and “log error when not persisted” cases.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
providers/fab/src/airflow/providers/fab/auth_manager/security_manager/override.py	Adds IntegrityError handling and DB verification to avoid noisy logs during concurrent FAB permission initialization.
providers/fab/tests/unit/fab/auth_manager/security_manager/test_override.py	Adds unit tests validating the new duplicate-handling behavior and the fallback error logging behavior.

[Lee-W]

nit but overall looks good

[jason810496]

Thanks for the fix. LGTM overall.