BugFix: Random test failure when tracking compilation time (#1713)

test: "tracks proper time of compiling the factory"
source: acceptance/activesupport_instrumentation_spec.rb:99

The test sporadically fails with a complitation time of 0:

The issue, is that the "factory_bot.compile_factory"
intrumentation is actually triggered twice, not just once.

First for :user and secondly for :configuration.

The :configuration compilation time, which can indeed be 0,
is the last one triggered, so that's the elapsed time recorded
by :time_to_execute.

By changing :time_to_execute to a hash, and recording the individual
compilations, we can check just the :user compilation time with
`time_to_execute[:user]`.

spec/acceptance/activesupport_instrumentation_spec.rb

@@ -97,13 +97,15 @@ def subscribed(callback, *args)
   end
 
   it "tracks proper time of compiling the factory" do
-    time_to_execute = 0
-    callback = ->(_name, start, finish, _id, _payload) { time_to_execute = finish - start }
+    time_to_execute = {user: 0}
+    callback = ->(_name, start, finish, _id, payload) {
+      time_to_execute[payload[:name]] = (finish - start)
+    }
     ActiveSupport::Notifications.subscribed(callback, "factory_bot.compile_factory") do
       FactoryBot.build(:user)
     end
 
-    expect(time_to_execute).to be > 0
+    expect(time_to_execute[:user]).to be > 0
   end
 
   it "builds the correct payload" do