Fix db downgrade check condition (apache#52982)

* fix rollback from airflow3

* use fab for test

* amend

* fix test

* revert condition fix and add shortcut if revisions are same

* updating revision to 2.10.3 in condition

* remove fab from tests

Author: vatsrahul1001

airflow-core/src/airflow/utils/db.py

@@ -1055,7 +1055,7 @@ def downgrade(*, to_revision, from_revision=None, show_sql_only=False, session:
     log.info("Attempting downgrade to revision %s", to_revision)
     config = _get_alembic_config()
     # Check if downgrade is less than 3.0.0 and requires that `ab_user` fab table is present
-    if _revision_greater(config, _REVISION_HEADS_MAP["3.0.0"], to_revision):
+    if _revision_greater(config, _REVISION_HEADS_MAP["2.10.3"], to_revision):
         unitest_mode = conf.getboolean("core", "unit_test_mode")
         if unitest_mode:
             try: