Move decomposition tests to nightly
What does this MR do and why?
Closes gitlab-org/quality/quality-engineering/team-tasks#2656 (closed)
Removes the end-to-end test jobs that run in a decomposed GitLab environment per-MR and moves them to Nightly.
To reduce pipeline duration, move these jobs to run on a Nightly basis, rather than per-MR, especially given that this work has occurred and has finished long ago. It is no longer necessary to run per-MR.
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