WIP: Add Multiple Clusters E2E test

What does this MR do?

Closes gitlab-org/quality/testcases#112 (closed)

Adds an end-to-end test for adding multiple clusters to a project

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

This test is another long-running test as it relies on two clusters to be spun up to use.