[sheriff] Disable test flaking on all platforms.

TBR=tmartino@chromium.org

Bug: 1084931
Change-Id: Ic89e67ad2f87e972aab271e3fb208bdd808920d2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2310808Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Auto-Submit: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790621}

tools/perf/core/minidump_unittest.py

@@ -34,12 +34,8 @@ class BrowserMinidumpTest(tab_test_case.TabTestCase):
   # Minidump symbolization doesn't work in ChromeOS local mode if the rootfs is
   # still read-only, so skip the test in that case.
   # TODO(crbug.com/1038043): Test is failing on chromeos-betty-chrome.
-  @decorators.Disabled(
-      'chromeos-local',
-      'chromeos-board-betty',
-      'chromeos-board-betty-pi-arc',
-      'win'  # https://crbug.com/1084931
-  )
+  # Flaky on all platforms: https://crbug.com/1084931
+  @decorators.Disabled('all')
   def testSymbolizeMinidump(self):
     # Wait for the browser to restart fully before crashing
     self._LoadPageThenWait('var sam = "car";', 'sam')