Handle transient MR query count spec [EE]

Addresses the following transient spec:

  1) Projects::MergeRequestsController GET show as json number of queries verifies number of queries
     Failure/Error: expect(recorded.count).to be_within(1).of(100)
       expected 93 to be within 1 of 100
     # ./spec/controllers/projects/merge_requests_controller_spec.rb:293:in `block (5 levels) in <top (required)>'