Remove duplicate shared example

What does this MR do and why?

I just found this accidentally while I was looking for something else.

This shared example seems to be a duplicate of https://gitlab.com/gitlab-org/gitlab/blob/89ee40a7450cc07f14e81dc9ea1d3661ed4b233a/spec/support/shared_examples/namespaces/members.rb#L3.

I'm not sure why RSpec doesn't emit shared example name clash warning though. 🤔 RSpec prints out warning if the same shared examples are defined twice within the same spec file or between files underspec/support/shared_examples folder, but it doesn't seem to print out warning when there is duplicate like this one.

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