Remove unneeded broken test

What does this MR do and why?

#407862 (closed) is a broken test since Group hooks are auto-disabled as of !114515 (merged).

We have tests of group hook auto-disabling behaviour already in ee/spec/models/hooks/group_hook_spec.rb so we can remove it.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #407862 (closed)