[legacy sf flag] - Remove enableNewFrontEnd()

There is no need to specially enable the new SF frontend
once the legacy frontend is removed. This method can be
removed from any test suites.

Bug: b/330785038
Test: presubmit
Test: atest LayerHistoryIntegrationTest
Change-Id: I2e94156c49b79bbcc779a65997e184a2e4eb1660
diff --git a/services/surfaceflinger/tests/unittests/LayerHistoryIntegrationTest.cpp b/services/surfaceflinger/tests/unittests/LayerHistoryIntegrationTest.cpp
index 2fb80b1..a61fa1e 100644
--- a/services/surfaceflinger/tests/unittests/LayerHistoryIntegrationTest.cpp
+++ b/services/surfaceflinger/tests/unittests/LayerHistoryIntegrationTest.cpp
@@ -1003,8 +1003,6 @@
         mappings.push_back(std::make_pair(kAppId1, kThreshold1));
         mappings.push_back(std::make_pair(kAppId2, kThreshold2));
 
-        mFlinger.enableNewFrontEnd();
-
         mScheduler->onActiveDisplayAreaChanged(DISPLAY_WIDTH * DISPLAY_HEIGHT);
         mScheduler->updateSmallAreaDetection(mappings);
     }
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index 4d9e339..85b1717 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -691,11 +691,6 @@
         return mFlinger->initTransactionTraceWriter();
     }
 
-    void enableNewFrontEnd() {
-        mFlinger->mLayerLifecycleManagerEnabled = true;
-        mFlinger->mLegacyFrontEndEnabled = false;
-    }
-
     void notifyExpectedPresentIfRequired(PhysicalDisplayId displayId, Period vsyncPeriod,
                                          TimePoint expectedPresentTime, Fps frameInterval,
                                          std::optional<Period> timeoutOpt) {