This commit fixes some warnings shown by `keystone-manage doctor`
command that are present in Keystone installed with default chart
configuration. In particular:
* Set max_toke_size=32 as this is correct value for uuid token provider.
* Enable caching using memcache by setting [cache] memcache_servers
option correctly in configmap-etc.yaml
Change-Id: I38cc7be577e0a7cd9be715e633f3637baafcc21b
Closes-Bug: 1693806