Fix StandardContext test

What does this MR do and why?

While working on adding is_gitlab_team_member to StandardContext in another MR I realized that the test for StandardContext hasn't kept up with the implementation. Therefor this update of the test.

ee/spec/lib/gitlab/tracking/standard_context_spec.rb was removed as there is no longer anything ee specific in the test.

MR acceptance checklist

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Related to #411277 (closed)