Remove all references to GIT_MODE from depot_tools

recipe_modules/bot_update/example.expected/tryjob_fail_patch.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "tryserver.chromium.linux",
       "--builder",
       "linux_rel",
       "--slave",
       "totallyaslave-c4",
       "--spec",
-      "cache_dir = '[GIT_CACHE]'\nsolutions = [{'deps_file': '.DEPS.git', 'managed': True, 'name': 'src', 'url': 'svn://svn.chromium.org/chrome/trunk/src'}]",
+      "cache_dir = '[GIT_CACHE]'\nsolutions = [{'deps_file': '.DEPS.git', 'managed': True, 'name': 'src', 'url': 'https://chromium.googlesource.com/chromium/src.git'}]",
       "--root",
       "src",
       "--revision_mapping_file",
       "{\"src\": \"got_cr_revision\"}",
       "--git-cache-dir",
       "[GIT_CACHE]",
       "--patch_url",
       "http://src.chromium.org/foo/bar",
       "--output_json",
       "/path/to/tmp/json",
@@ skipping 48 matching lines @@
       "@@@STEP_FAILURE@@@"
     ]
   },
   {
     "name": "$result",
     "reason": "Step('Patch failure') failed with return_code 1",
     "recipe_result": null,
     "status_code": 1
   }
 ]