[PATCH] pgarchives: Fix database install procedure: remove redundant tables in schema.sql

Hello,

While installing pgarchives, I've encountered issues that are addressed in this patch.
Django's model and schema.sql both contain tables that are necessary for
the execution of the application, but are mutually exclusive.
This is due to some fields in the "messages" table that cannot be defined in
django, and definition of tables in schema.sql that are already created
by django.

Additionally, I have two questions:
- Where is the "tsparser" parser defined? (See commit e05f813b of pgarchives).
It is used in schema.sql, but I haven't found its definition in the
pgarchives, pglister or pgweb repositories. Is it an alias to
pg_catalog.pg_ts_parser?
(I have been able to complete the install procedure by reverting e05f813b,
but I have no idea what the consequences are for the application)
- Same question for /usr/share/postgresql/12/tsearch_data/pg_dict.stop
I've found pg_dict.syn in pgweb, but not this file.

Cheers,
--
Célestin Matte