Add auth spans and remove deduplication code for scopes (#89804)

Adds more spans for timing in accesscontrol and remove permission deduplicating code after benchmarking

---------

Signed-off-by: Dave Henderson <dave.henderson@grafana.com>
Co-authored-by: Dave Henderson <dave.henderson@grafana.com>
Co-authored-by: Ieva <ieva.vasiljeva@grafana.com>

pkg/services/accesscontrol/acimpl/service_test.go

@@ -42,6 +42,7 @@ func setupTestEnv(t testing.TB) *Service {
 		registrations: accesscontrol.RegistrationList{},
 		roles:         accesscontrol.BuildBasicRoleDefinitions(),
 		store:         database.ProvideService(db.InitTestDB(t)),
+		tracer:        tracing.InitializeTracerForTest(),
 	}
 	require.NoError(t, ac.RegisterFixedRoles(context.Background()))
 	return ac