redhat_subscription: deprecate "pool" (#6650)
The "pool" option is slower to use, and the regexp may expand to broader
results than wanted. Because of that, deprecate it in favour of the
"pool_ids" options (which is much better), slating it for removal in
community.general 10.0.0.
(cherry picked from commit 61b889749e)
Co-authored-by: Pino Toscano <ptoscano@redhat.com>
