This config option in Keystone was deprecated for
removal since the Pike release and was removed in
the Rocky release.
We used this value to determine if the appropriate
memcache package was required which is causing issues
when puppet-oslo with manage_memcache_package is set to true
(default value is true).
This deprecates this parameter and removes the memcache
package installation logic which is superceeded by the
oslo::cache class since Rocky release.
Depends-On: https://review.openstack.org/#/c/632962/
Change-Id: I95a5982097529f119d99f0e7c77ac53d62da5733
9f8d2341e4