Change the wording from "Stop casting" to "Stop"

-The string is freezed. Reuse current "Stop" string

Bug: 153705889
Test: make -j42 RunSettingsRoboTests
Change-Id: I39184dcbfda5937677ab171a66ad5dcbbb8e6b68

src/com/android/settings/panel/MediaOutputPanel.java

@@ -167,7 +167,7 @@ public class MediaOutputPanel implements PanelContent, LocalMediaManager.DeviceC
 
     @Override
     public CharSequence getCustomizedButtonTitle() {
-        return mContext.getText(R.string.media_output_panel_stop_casting_button);
+        return mContext.getText(R.string.service_stop);
     }
 
     @Override