Add '--adb-keys-file $HOME/.android/*.pub' to all bot provision_devices calls.

scripts/slave/recipes/cronet.expected/android_cronet_armv6_builder.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport os, sys\n\nbuild_path = sys.argv[1]\nif os.path.exists(build_path):\n  for (path, dir, files) in os.walk(build_path):\n    for cur_file in files:\n      if cur_file.endswith('index.lock'):\n        path_to_file = os.path.join(path, cur_file)\n        print 'deleting %s' % path_to_file\n        os.remove(path_to_file)\n",
       "[SLAVE_BUILD]"
     ],
     "name": "cleanup index.lock",
     "~followup_annotations": [
@@ skipping 256 matching lines @@
       "@@@STEP_LOG_LINE@json.output@]@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/build/android/provision_devices.py",
       "-t",
-      "Release"
+      "Release",
+      "--adb-key-files /usr/local/google/home/navabi/.android/*.pub"
     ],
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "provision_devices"
   },
   {
     "cmd": [
       "python",
       "-u",
@@ skipping 90 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@import glob, os, sys@@@",
       "@@@STEP_LOG_LINE@python.inline@for report in glob.glob(sys.argv[1]):@@@",
       "@@@STEP_LOG_LINE@python.inline@  with open(report, 'r') as f:@@@",
       "@@@STEP_LOG_LINE@python.inline@    for l in f.readlines():@@@",
       "@@@STEP_LOG_LINE@python.inline@      print l@@@",
       "@@@STEP_LOG_LINE@python.inline@  os.remove(report)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   }
 ]