RESTRICT AUTOMERGE: Update tests to treat enable_small_area_detection as true

Explictitly set enable_small_area_detection flag to true so the tests
could always pass.

Bug: 323232586
Test: libsurfaceflinger_unittest
Change-Id: Ie21becc71f968fa8658824ef143dbb7fe4f110a1

Author: Arthur Hung

services/surfaceflinger/tests/unittests/LayerHistoryIntegrationTest.cpp

@@ -1030,6 +1030,7 @@ class SmallAreaDetectionTest : public LayerHistoryIntegrationTest {
 };
 
 TEST_F(SmallAreaDetectionTest, SmallDirtyLayer) {
+    SET_FLAG_FOR_TEST(flags::enable_small_area_detection, true);
     auto layer = createLegacyAndFrontedEndLayer(1);
 
     nsecs_t time = systemTime();
@@ -1047,6 +1048,7 @@ TEST_F(SmallAreaDetectionTest, SmallDirtyLayer) {
 }
 
 TEST_F(SmallAreaDetectionTest, NotSmallDirtyLayer) {
+    SET_FLAG_FOR_TEST(flags::enable_small_area_detection, true);
     auto layer = createLegacyAndFrontedEndLayer(1);
 
     nsecs_t time = systemTime();
@@ -1064,6 +1066,7 @@ TEST_F(SmallAreaDetectionTest, NotSmallDirtyLayer) {
 }
 
 TEST_F(SmallAreaDetectionTest, smallDirtyLayerWithMatrix) {
+    SET_FLAG_FOR_TEST(flags::enable_small_area_detection, true);
     auto layer = createLegacyAndFrontedEndLayer(1);
 
     nsecs_t time = systemTime();