WIP: Geo: Test wiki HTTP push to secondary

What does this MR do?

Add a test for HTTP pushes of wiki commits to secondary node of a Geo instance.

Steps:

• Create project with wiki on primary node
• Push a wiki commit to the secondary node
• Confirm that the commit is displayed on both nodes

This test required adding geo-specific wait methods to the wiki show page.

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content