[Perf] Disable failing browse:media:imgur stories

Disable the following two failing stories on Linux:
* system_health.common_desktop/browse:media:imgur
* system_health.memory_desktop/browse:media:imgur

Notry: true
TBR: wenbinzhang@google.com
Bug: 1154753
Change-Id: Ibb654a2736c14e2f74c986475ca705004dc3da16
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2570739Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833183}

tools/perf/expectations.config

@@ -287,6 +287,7 @@ crbug.com/1044682 [ desktop ] system_health.common_desktop/browse:tools:gmail-op
 crbug.com/1044682 [ desktop ] system_health.common_desktop/browse:tools:gmail-search:2020 [ Skip ]
 crbug.com/1044682 [ desktop ] system_health.common_desktop/browse:tools:gmail-compose:2020 [ Skip ]
 crbug.com/1150432 [ linux ] system_health.common_desktop/long_running:tools:gmail-background [ Skip ]
+crbug.com/1154753 [ linux ] system_health.common_desktop/browse:media:imgur [ Skip ]
 
 # Benchmark: system_health.common_mobile
 crbug.com/1007355 [ android-go android-webview ] system_health.common_mobile/load:media:imgur:2018 [ Skip ]
@@ -372,6 +373,7 @@ crbug.com/1147969 [ fuchsia ] system_health.memory_desktop/long_running:tools:gm
 crbug.com/1147969 [ fuchsia ] system_health.memory_desktop/long_running:tools:gmail-foreground [ Skip ]
 crbug.com/1147969 [ fuchsia ] system_health.memory_desktop/multitab:misc:typical24 [ Skip ]
 crbug.com/1147969 [ fuchsia ] system_health.memory_desktop/multitab:misc:typical24:2018 [ Skip ]
+crbug.com/1154753 [ linux ] system_health.memory_desktop/browse:media:imgur [ 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 ]