Add Geo wiki ssh push to secondary spec

What does this MR do?

Addresses: gitlab-org/quality/testcases#198 (closed)

• Updates wiki and wiki-push resources to fetch repository ssh location
• Adds test to confirm that a wiki commit pushed to a secondary Geo node via SSH is (1) proxied to the primary node and (2) replicated to the secondary node.

Note to reviewers: to run test from gitlab/qa against a live (testing) Geo instance:

CHROME_HEADLESS=false bundle exec bin/qa QA::EE::Scenario::Test::Geo --primary-address http://jslqa3-primary-geo.gogitlab.ml --primary-name gitlab-primary --secondary-address http://jslqa3-secondary-geo.gogitlab.ml --secondary-name gitlab-secondary --without-setup -- qa/specs/features/ee/browser_ui/geo/wiki_ssh_push_to_secondary_spec.rb

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides