Remove useOverflowInset flag as we rolled out 100% to public for over three months

Summary:
This was shipped in D36990986 (df80ed4) but backed out last year in D37074879 (59476d0), as we want to wait for some performance comparison results to come out.

Remove overflow inset optimization flags as they've been rolled out 100% to public.

Changelog:
[Android][Internal] - Clean up feature flags for overflowInset

Reviewed By: javache

Differential Revision: D43070494

fbshipit-source-id: dbf5aed9b2b5d3db1ad351bc208cb2016dc62e40

Author: Xin Chen

ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java

@@ -67,9 +67,6 @@ public class ReactFeatureFlags {
   /** Enables or disables calculation of Transformed Frames */
   public static boolean calculateTransformedFramesEnabled = false;
 
-  /** Feature Flag to use overflowInset values provided by Yoga */
-  public static boolean useOverflowInset = false;
-
   public static boolean dispatchPointerEvents = false;
 
   /** Feature Flag to enable the pending event queue in fabric before mounting views */

ReactAndroid/src/main/java/com/facebook/react/uimanager/TouchTargetHelper.java

@@ -19,7 +19,6 @@
 import androidx.annotation.Nullable;
 import com.facebook.react.bridge.JSApplicationIllegalArgumentException;
 import com.facebook.react.bridge.UiThreadUtil;
-import com.facebook.react.config.ReactFeatureFlags;
 import com.facebook.react.touch.ReactHitSlopView;
 import com.facebook.react.uimanager.common.ViewUtil;
 import java.util.ArrayList;
@@ -192,7 +191,6 @@ private static View findTouchTargetView(
           // If the touch point is outside of the overflowinset for the view, we can safely ignore
           // it.
           if (ViewUtil.getUIManagerType(view.getId()) == FABRIC
-              && ReactFeatureFlags.useOverflowInset
               && !isTouchPointInViewWithOverflowInset(eventCoords[0], eventCoords[1], view)) {
             return null;
           }

ReactAndroid/src/main/jni/react/fabric/FabricMountingManager.cpp

@@ -40,7 +40,6 @@ FabricMountingManager::FabricMountingManager(
     std::shared_ptr<const ReactNativeConfig> &config,
     global_ref<jobject> &javaUIManager)
     : javaUIManager_(javaUIManager),
-      useOverflowInset_(getFeatureFlagValue("useOverflowInset")),
       reduceDeleteCreateMutation_(
           getFeatureFlagValue("reduceDeleteCreateMutation")) {
   CoreFeatures::enableMapBuffer = getFeatureFlagValue("useMapBufferProps");
@@ -404,8 +403,7 @@ void FabricMountingManager::executeMount(
             // children of the current view. The layout of current view may not
             // change, and we separate this part from layout mount items to not
             // pack too much data there.
-            if (useOverflowInset_ &&
-                (oldChildShadowView.layoutMetrics.overflowInset !=
+            if ((oldChildShadowView.layoutMetrics.overflowInset !=
                  newChildShadowView.layoutMetrics.overflowInset)) {
               cppUpdateOverflowInsetMountItems.push_back(
                   CppMountItem::UpdateOverflowInsetMountItem(
@@ -461,9 +459,8 @@ void FabricMountingManager::executeMount(
             // children of the current view. The layout of current view may not
             // change, and we separate this part from layout mount items to not
             // pack too much data there.
-            if (useOverflowInset_ &&
-                newChildShadowView.layoutMetrics.overflowInset !=
-                    EdgeInsets::ZERO) {
+            if (newChildShadowView.layoutMetrics.overflowInset !=
+                EdgeInsets::ZERO) {
               cppUpdateOverflowInsetMountItems.push_back(
                   CppMountItem::UpdateOverflowInsetMountItem(
                       newChildShadowView));

ReactAndroid/src/main/jni/react/fabric/FabricMountingManager.h

@@ -69,7 +69,6 @@ class FabricMountingManager final {
   butter::map<SurfaceId, butter::set<Tag>> allocatedViewRegistry_{};
   std::recursive_mutex allocatedViewsMutex_;
 
-  bool const useOverflowInset_{false};
   bool const reduceDeleteCreateMutation_{false};
 
   jni::local_ref<jobject> getProps(