Splits pipelines specs from main usage quotas spec file

What does this MR do and why?

This is a second step in Refactor Usage Quotas feature specs to have ded... (#381108 - closed).

This MR pulls out Pipelines-related specs from the main Usage Quotas spec file into it's own file.

Screenshots or screen recordings

n/a

How to set up and validate locally

rspec ee/spec/features/groups/usage_quotas/

MR acceptance checklist

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