Update generate_buildbot_json.py to match manual change to chromium.gpu.fyi.json

BUG=670817
TBR=kbr@chromium.org,jmadill@chromium.org
NOTRY=true
NOPRESUBMIT=true
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2577803002
Cr-Commit-Position: refs/heads/master@{#438631}

content/test/gpu/generate_buildbot_json.py

@@ -1504,7 +1504,7 @@ def generate_gtest(tester_name, tester_config, test, test_config, is_fyi):
           {
             'cipd_package': 'infra/tools/luci/logdog/butler/${platform}',
             'location': 'bin',
-            'revision': 'git_revision:3ff24775a900b675866fbcacf2a8f98a18b2a16a'
+            'revision': 'git_revision:25755a2c316937ee44a6432163dc5e2f9c85cf58'
           }
         ],
         'output_links': [