`IMPORT FOREIGN SCHEMA` doesn't add to metadata when use_citus_managed_tables is on

[agedemenli]

We add newly created tables to Citus metadata when citus.use_citus_managed_tables is set to on. See #5440

This works for foreign tables as well. (See #5461)

But Citus doesn't add foreign tables that are imported from a schema to metadata, probably because of the

if (context == PROCESS_UTILITY_TOPLEVEL &&

check in utility_hook.c.