Disable minidump symbolization tests on Mac

Disables the Telemetry minidump symbolization tests on Mac, as they are
currently failing on some 10.15.5 machines due to Xcode not being set up
properly for Telemetry tests, and newly reinstalled machines do not have
a system-wide installation anymore.

TBR=johnchen@chromium.org

Bug: 1110441
Change-Id: I2e9f3d33a1086db24c07f167f5ab376a2a564146
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2324606Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792534}

tools/perf/core/minidump_unittest.py

@@ -35,6 +35,7 @@ class BrowserMinidumpTest(tab_test_case.TabTestCase):
   # still read-only, so skip the test in that case.
   @decorators.Disabled(
       'chromeos-local',
+      'mac',  #https://crbug.com/1110441
       'win'  # https://crbug.com/1084931
   )
   def testSymbolizeMinidump(self):
@@ -80,6 +81,7 @@ class BrowserMinidumpTest(tab_test_case.TabTestCase):
   # still read-only, so skip the test in that case.
   @decorators.Disabled(
       'chromeos-local',
+      'mac',  # https://crbug.com/1110441
       'win'  # https://crbug.com/1084931
   )
   def testMultipleCrashMinidumps(self):