Suppress metadata sync for vanilla regress test suite; this enables

all Postgres DDL commands to compelte without being propagated by
Citus.

src/test/regress/pg_regress_multi.pl

@@ -511,6 +511,9 @@ if($vanillatest)
 
     # we disable some restrictions for local objects like local views to not break postgres vanilla test behaviour.
     push(@pgOptions, "citus.enforce_object_restrictions_for_local_objects=false");
+
+    # we disable metadata synchronization to enable postgres vanilla DDL tests to pass.
+    push(@pgOptions, "citus.enable_metadata_sync=false");
 }
 
 if ($useMitmproxy)