Make Geo Selective Sync More Clear

What does this MR do?

Closes #11165 (closed)

Currently it is not very clear when a Node is set to Selective Sync.

This MR adds some conditional information about Selective Synchronization to the Header of the Node Card when it is active.

This also has a pending change of unifying the term Namespaces into Groups for the sake of consistency in Geo.

Screenshots

	Groups	Shards
before
after

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Closes #11165 (closed)