Restore refresh spinner fix (#30978)

Summary:
Fixes #30912
Reverts #31024 which did not fix the issue

This fix was removed in #28236, however it caused bug #7976 to resurface, as reported in #30912

Pull Request resolved: #30978

Test Plan:
This code had been present for quite some time before being removed in #28236

## Changelog

[Internal] [fixed] - regression with refresh control

Reviewed By: p-sun

Differential Revision: D26981600

Pulled By: PeteTheHeat

fbshipit-source-id: 2560e7dba1cfd6ed41d98f2c9ff4cd07a0e5fa24

Author: swrobel

React/Views/RefreshControl/RCTRefreshControl.m

@@ -43,6 +43,11 @@ - (void)layoutSubviews
   [super layoutSubviews];
   [self _applyProgressViewOffset];
 
+  // Fix for bug #7976
+  if (self.backgroundColor == nil) {
+    self.backgroundColor = [UIColor clearColor];
+  }
+  
   // If the control is refreshing when mounted we need to call
   // beginRefreshing in layoutSubview or it doesn't work.
   if (_currentRefreshingState && _isInitialRender) {
@@ -51,18 +56,6 @@ - (void)layoutSubviews
   _isInitialRender = false;
 }
 
-- (void)didMoveToWindow
-{
-  [super didMoveToWindow];
-
-  // Since iOS 14 there seems to be a bug where refresh control becomes
-  // visible if the view gets removed from window then added back again.
-  // Calling endRefreshing fixes the layout.
-  if (!_currentRefreshingState) {
-    [super endRefreshing];
-  }
-}
-
 - (void)beginRefreshingProgrammatically
 {
   UInt64 beginRefreshingTimestamp = _currentRefreshingStateTimestamp;