chore: correct pgbouncer.get_auth ownership accordingly post upgrade

[dragarcia]

Standardize with:

postgres/ansible/files/admin_api_scripts/pg_upgrade_scripts/common.sh

Lines 532 to 540 in 074a2ec

	-- #incident-2024-09-12-project-upgrades-are-temporarily-disabled
	do $$
	begin
	if exists (select from pg_authid where rolname = 'pg_read_all_data') then
	execute('grant pg_read_all_data to postgres');
	end if;
	end
	$$;
	grant pg_signal_backend to postgres;

[soedirgo]

https://supabase.slack.com/archives/C01D6TWFFFW/p1730878084036359?thread_ts=1730338211.353519&cid=C01D6TWFFFW