refactor: remove wal-g files from multigres image

Multigres uses pgbackrest for backups. Remove the wal-g config and helper
scripts inherited from the supabase base image.

Author: mkindahl

Dockerfile-multigres

@@ -52,6 +52,12 @@ COPY --chmod=0755 docker/pgctld/pgctld /usr/local/bin/pgctld
 # config from postgresql.conf.tmpl and passes it directly to PostgreSQL, so the
 # supabase base config (including wal-g and data_directory settings) is never loaded.
 
+# wal-g is not used in Multigres (pgbackrest handles backups); remove inherited files.
+RUN rm -f \
+    /etc/postgresql-custom/wal-g.conf \
+    /home/postgres/wal_fetch.sh \
+    /root/wal_change_ownership.sh
+
 # Preamble SQL run before init-scripts: creates the postgres role and sets DB ownership.
 # The wrapper script then passes --pg-initdb-sql-dir to run init-scripts (as postgres)
 # and migrations (as supabase_admin) in sorted order.