Allow Galaxy headnode to connect to 'gxitproxy' database as user 'gal…

…axy'

A separate database for the Galaxy Interactive Tools Proxy is needed to store the interactive tools session map on PostgreSQL.

@jdavcs wrote (galaxyproject/galaxy#18481 (comment)):
> I assume the gxitproxy table is meant to be part of the main galaxy's database (as per #1251)? If so, that may break things. Galaxy does not assume the existence of tables in its database that are not defined in its model (except for this one case). Thus, db schema migration logic may break, now or in the future when we add some feature that scans the database).

This commit is part of the migration procedure to store interactive tool sessions in PostgreSQL database 'gxitproxy' (#1251). In addition to merging it into `master`, please complete step (1) of the migration (read below).

> On Postgres, create the database gxitproxy and set the galaxy user as its owner. Create also the table gxitproxy on beforehand (gx-it-proxy refuses to run without it). For greater details you may have a look at the updated GTN training (https://github.com/usegalaxy-eu/infrastructure-playbook/pull/galaxyproject/training-material/pull/5179).

group_vars/sn05.yml

@@ -88,6 +88,7 @@ postgresql_pg_hba_conf:
   - "host    tiaas           tiaas           132.230.223.239/32      md5"
   - "host    tiaas           tiaas           132.230.223.238/32      md5"
   - "host    tiaas           tiaas           10.5.68.237/32          md5"
+  - "host    gxitproxy       galaxy          132.230.223.239/32      md5"
   - "host    galaxy-test     galaxy-test     132.230.223.239/32      md5"
   - "host    galaxy-test     galaxy-test     10.5.68.0/24            md5"
   - "host    galaxy          galaxyftp       132.230.224.107/32      md5"