Add Admin to Client Port Set

The SDKs poll the admin port on non-data nodes (probably data nodes too).
Also for things like creating buckets and users via an application, this needs port 8091.

Currently setting exposedFeatures to 'client' doesn't include the admin ports, so this may cause issues with clients connected to exposed pods.
We should include the admin ports for the 'client' exposed feature to ensure that there aren't any inconsistencies or potential gotchas when using this setting.

Workaround is easy enough, you need specify 'admin' as an exposedFeature as well as 'client'.