Disable TestShardingMapGenerator.testGeneratePerfSharding everywhere

NOTRY=true
NOTREECHECKS=true
TBR=thakis@chromium.org

Bug: 855689
Change-Id: Ie4c77e59bd642d581a73954723470d5920ae8865
Reviewed-on: https://chromium-review.googlesource.com/1112946
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#569891}

tools/perf/core/sharding_map_generator_unittest.py

@@ -46,7 +46,9 @@ class TestShardingMapGenerator(unittest.TestCase):
     finally:
       os.remove(map_path)
 
-  @decorators.Disabled('android', 'win', 'linux')
+  # Failing everywhere (see
+  # https://chromium-review.googlesource.com/c/chromium/src/+/1112978)
+  @decorators.Disabled('all')
   def testGeneratePerfSharding(self):
     path_output = tempfile.mkstemp(suffix='.json')[1]
     path_results = tempfile.mkstemp(suffix='.json')[1]