Clean up and remove test since unit testing on mac not set up?

Author: justinmc

shell/platform/darwin/macos/framework/Source/FlutterViewController.mm

@@ -549,10 +549,6 @@ - (NSDictionary*)clipboardHasStrings {
   NSString* string = data[@"text"];
   BOOL hasStrings = string.length > 0;
   return @{@"value" : @(hasStrings)};
-  /*
-  UIPasteboard* pasteboard = [UIPasteboard generalPasteboard];
-  return @{@"value" : @(pasteboard.hasStrings)};
-  */
 }
 
 #pragma mark - FlutterViewReshapeListener