Use hard-coded group paths for truncated export filename spec

What does this MR do?

On CI the auto-generated group paths can become so long that the project path is truncated away, this fixese that by using hard-coded group paths.

Fixes #323349 (closed)

I reproduced the failure / verified the fix locally by adding this to the spec:

    before do
      1000.times { build(:group) }
    end

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Does this MR meet the acceptance criteria?

Conformity

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Related to #323349 (closed)