Bug 1544702 Clear app data between tests when running mobile warm raptor tests r=rwood

Differential Revision: https://phabricator.services.mozilla.com/D27652

--HG--
extra : moz-landing-system : lando

testing/raptor/raptor/raptor.py

@@ -809,6 +809,7 @@ class RaptorAndroid(Raptor):
         if test.get('playback', None) is not None:
             self.turn_on_android_app_proxy()
 
+        self.clear_app_data()
         self.copy_profile_onto_device()
 
         # now start the browser/app under test