Make performance bar enabled checks consistent

Previously, we called the `peek_enabled?` method like so:

    prepend_before_action :set_peek_request_id, if: :peek_enabled?

Now we don't have a `set_peek_request_id` method, so we don't need that
line. However, the `peek_enabled?` part had a side-effect: it would also
populate the request store cache for whether the performance bar was
enabled for the current request or not.

This commit makes that side-effect explicit, and replaces all uses of
`peek_enabled?` with the more explicit
`Gitlab::PerformanceBar.enabled_for_request?`. There is one spec that
still sets `SafeRequestStore[:peek_enabled]` directly, because it is
contrasting behaviour with and without a request store enabled.

The upshot is:

1. We still set the value in one place. We make it more explicit that
   that's what we're doing.
2. Reading that value uses a consistent method so it's easier to find in
   future.

1 files changed, 1 insertions, 1 deletions

diff --git a/spec/lib/peek/views/rugged_spec.rb b/spec/lib/peek/views/rugged_spec.rb
index d07d6b51a1f..b9507f772d2 100644
--- a/spec/lib/peek/views/rugged_spec.rb
+++ b/spec/lib/peek/views/rugged_spec.rb
@@ -8,7 +8,7 @@ describe Peek::Views::Rugged, :request_store do
   let(:project) { create(:project) }
 
   before do
-    allow(Gitlab::RuggedInstrumentation).to receive(:peek_enabled?).and_return(true)
+    allow(Gitlab::PerformanceBar).to receive(:enabled_for_request?).and_return(true)
   end
 
   it 'returns no results' do