[Sheriff] Disable system_health.memory_desktop/load:news:bbc:2018 on Linux

TBR=ulan@chromium.org

Bug: 999004
Change-Id: I941cf118d9f0a70d4e714989b0b75d13790fd67d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1778877Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692621}

tools/perf/expectations.config

@@ -334,6 +334,7 @@ crbug.com/942952 [ chromeos ] system_health.memory_desktop/browse:news:hackernew
 crbug.com/959418 [ chromeos ] system_health.memory_desktop/long_running:tools:gmail-background [ Skip ]
 crbug.com/959418 [ chromeos ] system_health.memory_desktop/load:games:spychase:2018 [ Skip ]
 crbug.com/959418 [ chromeos ] system_health.memory_desktop/long_running:tools:gmail-foreground [ Skip ]
+crbug.com/999004 [ linux ] system_health.memory_desktop/load:news:bbc:2018 [ Skip ]
 
 # Benchmark: system_health.memory_mobile
 crbug.com/914390 [ android-nexus-5 ] system_health.memory_mobile/browse:chrome:newtab [ Skip ]