Revert "[Settings] Convert to getSystemService(Class<T>)"

Revert submission 1645152-getSystemService(Class<T>)

Reason for revert: Fix JUnit test failure
Reverted Changes:
I1b4812044:[Settings] Convert to getSystemService(Class<T>)
I278951c24:[Settings] Support getSystemService(Class<T>)

Change-Id: I864a40f82ba9cb4170900ac0c1d77f781b17341f

src/com/android/settings/wifi/tether/TetherService.java

@@ -255,7 +255,7 @@ public class TetherService extends Service {
     }
 
     private void disableTethering(final int tetheringType) {
-        final TetheringManager tm = getSystemService(TetheringManager.class);
+        final TetheringManager tm = (TetheringManager) getSystemService(Context.TETHERING_SERVICE);
         tm.stopTethering(tetheringType);
     }