[ios] Telemetry button in modal view controllers (#9027)

Fixes #8980.

Author: jmkiley

platform/ios/src/MGLMapView.mm

@@ -1999,9 +1999,10 @@ - (void)presentTelemetryAlertController
     }];
     [alertController addAction:participateAction];
 
-    [self.window.rootViewController presentViewController:alertController
-                                                 animated:YES
-                                               completion:NULL];
+    UIViewController *viewController = [self.window.rootViewController mgl_topMostViewController];
+    [viewController presentViewController:alertController
+                                 animated:YES
+                               completion:NULL];
 }
 
 #pragma mark - Properties -