Remove run loop spin for search action.

The remote call for setting search action doesn't need to spin test runloop, because the remote execution doesn't require dispatching to other threads. But keeping runloop spinning would require adding a separate async API for Swift async/await. For simplicity, removing the runloop spinning and add comment.

PiperOrigin-RevId: 569102794

Author: AlbertWang0116

TestLib/EarlGreyImpl/GREYElementInteractionProxy.m

@@ -125,9 +125,11 @@ - (void)assertWithMatcher:(id<GREYMatcher>)matcher
                     onElementWithMatcher:(id<GREYMatcher>)matcher {
   GREYThrowOnNilParameterWithMessage(action, @"Action can't be nil.");
   GREYThrowOnNilParameterWithMessage(matcher, @"Matcher can't be nil.");
-  GREYExecuteSyncBlockInBackgroundQueue(^{
-    [self->_remoteElementInteraction usingSearchAction:action onElementWithMatcher:matcher];
-  });
+  // The remote interaction completes the whole execution within the target thread. If this is
+  // changed at remote, the method call below should be wrapped with
+  // `GREYExecuteSyncBlockInBackgroundQueue`, and a completion handler version of this API should be
+  // provided for Swift async test.
+  [self->_remoteElementInteraction usingSearchAction:action onElementWithMatcher:matcher];
   return self;
 }