Gitlab runner helm test upgrade support

Three separate upgrades to Gitlab Runner linked below all failed the helm test in the upgrade stage the same way. This seems to consistently be a problem with upgrades which means we are not effectively testing upgrades in CI. We should update the helm test to account for this - I suspect we need to add some conditional logic to handle running a new pipeline when one has already run.

https://repo1.dso.mil/platform-one/big-bang/bigbang/-/jobs/13893050

• Package pipeline: https://repo1.dso.mil/platform-one/big-bang/apps/developer-tools/gitlab-runner/-/jobs/13872184

https://repo1.dso.mil/platform-one/big-bang/bigbang/-/jobs/12625819

• Package pipeline: https://repo1.dso.mil/platform-one/big-bang/apps/developer-tools/gitlab-runner/-/jobs/12625081

https://repo1.dso.mil/platform-one/big-bang/bigbang/-/jobs/12280136

• Package pipeline (upgrade skipped): https://repo1.dso.mil/platform-one/big-bang/apps/developer-tools/gitlab-runner/-/merge_requests/53

Acceptance criteria:

• Helm test updated to properly run on upgrades