Bot_update recipe output: Add 'Try Rebasing' to patch failure output

I still see confusion around patch failures.  This should clearify things.

BUG=

Review-Url: https://codereview.chromium.org/2231953002

recipe_modules/bot_update/api.py

@@ -276,7 +276,7 @@ class BotUpdateApi(recipe_api.RecipeApi):
             # This is download failure, hence an infra failure.
             # Sadly, python.failing_step doesn't support kwargs.
             self.m.python.inline(
-                'Patch failure',
+                'Patch failure - Try Rebasing',
                 ('import sys;'
                  'print "Patch download failed. See bot_update step for'
                  ' details";sys.exit(1)'),

recipe_modules/bot_update/example.expected/tryjob_fail_patch_download.json

@@ -65,7 +65,7 @@
       "-u",
       "import sys;print \"Patch download failed. See bot_update step for details\";sys.exit(1)"
     ],
-    "name": "Patch failure",
+    "name": "Patch failure - Try Rebasing",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
       "@@@STEP_LOG_LINE@python.inline@import sys;print \"Patch download failed. See bot_update step for details\";sys.exit(1)@@@",
@@ -75,7 +75,7 @@
   },
   {
     "name": "$result",
-    "reason": "Infra Failure: Step('Patch failure') returned 1",
+    "reason": "Infra Failure: Step('Patch failure - Try Rebasing') returned 1",
     "recipe_result": null,
     "status_code": 1
   }