Update script tests to use new gluon script service account

The current Gitlab gluon script tests rely on the Role/RoleBinding provided here to run kubectl commands: https://repo1.dso.mil/big-bang/product/packages/gitlab/-/blob/main/chart/templates/bigbang/allow-gitlab-sa-to-exec-pods.yaml which grants permission (albeit temporarily) to all SA in the gitlab namespace.

Ideally we'd have a specific service account to hang these permissions. When this issue is addressed we should adopt the new service account.

Blocked by gluon#40 (closed)