Retest GitlabHQ and XL Import on Staging

In addition to the 10x testing we are doing in development environments, we would like to run a test import on Staging again to validate our test results.

Related issue: #196540 (closed)

• Coordinate test timing
• Ensure test import results are set to confidential
• Gather metrics and compare results using rake task ...

This will require assistance from @cmiskell and @mwasilewski-gitlab

@gl-memory