Use unique group path and update e2e test MR template

What does this MR do?

• Updates access termination end-to-end tests to use unique group paths
• Update new end-to-end test MR template to note that a group should not be removed unless it uses a unique path.

Related issue: #324422 (closed)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

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• Documentation (if required)
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• Style guides
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• [-] Separation of EE specific content