Disable load:tools:dropbox:2019 for all android bots.

I forgot to include system_health.common_mobile/load:tools:dropbox:2019

NOTRY=true
TBR=crouleau@chromium.org
CC=pasko@chromium.org,crouleau@chromium.org,chrome-android-perf-status@chromium.org,charliea@chromium.org,sullivan@chromium.org,tdresser@chromium.org,chrome-speed-metrics-dev@chromium.org
BUG=1039277

Change-Id: I2578885c2079e65a74881f40a0e88721b905d8f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1983210Reviewed-by: Stephen Nusko <nuskos@chromium.org>
Commit-Queue: Stephen Nusko <nuskos@chromium.org>
Auto-Submit: Stephen Nusko <nuskos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#728543}

tools/perf/expectations.config

@@ -345,6 +345,7 @@ crbug.com/1014655 [ android-webview ] system_health.common_mobile/browse:social:
 crbug.com/1036141 [ android-webview ] system_health.common_mobile/browse:shopping:lazada:2019 [ Skip ]
 crbug.com/1036143 [ android-pixel-2 ] system_health.common_mobile/browse:chrome:omnibox:2019 [ Skip ]
 crbug.com/1037687 [ android ] system_health.common_mobile/browse:social:pinterest_infinite_scroll:2019 [ Skip ]
+crbug.com/1039277 [ android ] system_health.common_mobile/load:tools:dropbox:2019 [ Skip ]
 
 # Benchmark: system_health.memory_desktop
 crbug.com/1027686 [ linux ] system_health.memory_desktop/browse:social:tumblr_infinite_scroll:2018 [ Skip ]