fix: disable client connections during upgrade

Author: soedirgo

ansible/files/admin_api_scripts/pg_upgrade_scripts/common.sh

@@ -93,6 +93,9 @@ begin;
 create role supabase_tmp superuser;
 set session authorization supabase_tmp;
 
+alter database postgres connection limit 0;
+select pg_terminate_backend(pid) from pg_stat_activity where backend_type = 'client backend' and pid != pg_backend_pid();
+
 do $$
 begin
   if exists (select from pg_extension where extname = 'timescaledb') then
@@ -509,6 +512,8 @@ begin
 end
 $$;
 
+alter database postgres connection limit -1;
+
 set session authorization supabase_admin;
 drop role supabase_tmp;
 commit;