Fix CI Variable spec

What does this MR do?

Addressing test failure #246791 (closed)

• Adding wait logic after adding CI variable
• Also I noticed that the test were revisiting the CI/CD settings page and re-expanding the CI/CD session so I made adjustments there as well, hopefully that will reduce the flakiness.

Conformity

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

Related to #246791 (closed)