CVE-2026-48726: Apache Airflow: revoke_token() unreachable in FabAuthManager / KeycloakAuthManager logout path

A bug in Apache Airflow's auth manager logout handling left previously-issued JWT tokens valid after the user clicked logout in the UI: the logout flow for FabAuthManager and KeycloakAuthManager did not actually reach the underlying revoketoken() call, so the JWT remained accepted by the API server until its natural expiry. An attacker holding a previously-issued JWT for a logged-out user could continue to make authenticated API calls as that user. Affects deployments configured with FabAuthManager or KeycloakAuthManager (the bug does not affect SimpleAuthManager). This is a residual gap in the fix for CVE-2025-57735, which addressed cookie-side invalidation in PR #57992 / PR #61339 but did not cover the provider-side revoketoken() reachability in the FAB / Keycloak code paths. Users who already upgraded for CVE-2025-57735 should additionally upgrade to apache-airflow 3.2.2 or later to cover the FAB / Keycloak logout paths.