Tighten some regexes with proper character escaping in pg_dump TAP tests

Some tests have been using regular expressions which have been lax in
escaping dots, which may cause tests to pass when they should not.  This
make the whole set of tests more robust where needed.

Author: David Rowley
Reviewed-by: Daniel Gustafsson, Michael Paquier
Discussion: https://postgr.es/m/CAKJS1f9jD8aVo1BTH+Vgwd=f-ynbuRVrS90XbWMT6UigaOQJTA@mail.gmail.com