Skipping flaky benchmark tests

benchmarks.system_health_smoke_test.SystemHealthBenchmarkSmokeTest.system_health.memory_desktop/browse:media:googleplaystore:2018
benchmarks.system_health_smoke_test.SystemHealthBenchmarkSmokeTest.system_health.memory_desktop/load:social:vk:2018
benchmarks.system_health_smoke_test.SystemHealthBenchmarkSmokeTest.system_health.memory_desktop/browse_accessibility:tech:codesearch:2018

TBR=sullivan@chromium.org

Bug: 1097065
Change-Id: Ibc1da2f9e0628177182eb61c16401368cae35ba9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2253979Reviewed-by: Andy Paicu <andypaicu@chromium.org>
Commit-Queue: Andy Paicu <andypaicu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780340}

tools/perf/expectations.config

@@ -358,6 +358,9 @@ crbug.com/1017346 [ desktop ] system_health.memory_desktop/browse:media:youtube:
 crbug.com/1042632 [ win ] system_health.memory_desktop/load:tools:gmail:2019 [ Skip ]
 crbug.com/1042632 [ win ] system_health.memory_desktop/browse:social:tumblr_infinite_scroll:2018 [ Skip ]
 crbug.com/956191 [ win7 ] system_health.memory_desktop/browse:news:nytimes:2020 [ Skip ]
+crbug.com/1097065 [ linux ] system_health.memory_desktop/browse:media:googleplaystore:2018 [ Skip ]
+crbug.com/1097065 [ linux ] system_health.memory_desktop/load:social:vk:2018 [ Skip ]
+crbug.com/1097065 [ linux ] system_health.memory_desktop/browse_accessibility:tech:codesearch:2018 [ Skip ]
 
 # Memory dumps don't work at the moment for Google Earth, see the issue.
 crbug.com/1057035 system_health.memory_desktop/browse:tools:earth:2020 [ Skip ]