(local_table_join.sql) With citus_set_coordinator_host, direct joins between reference and postgres tables succeeds although citus.local_table_join_policy = 'never'

Repro Steps (derived from local_table_join.sql):

```
SET citus.local_table_join_policy TO 'never';
CREATE TABLE postgres_table (key int, value text, value_2 jsonb);
CREATE TABLE reference_table (key int, value text, value_2 jsonb);
SELECT create_reference_table('reference_table');
create_reference_table
---------------------------------------------------------------------

(1 row)

SELECT count(*) FROM postgres_table JOIN reference_table USING(key);
count
-------
100
(1 row)
```

This scenario is suppposed to fail. And If we remove the coordinator, it fails with

```
ERROR: direct joins between distributed and local tables are not supported
HINT: Use CTE's or subqueries to select from local tables and use them in joins
```