Disable startup.mobile/maps_pwa:with_http_cache on android pixel 2.

This with a high flake rate.

BUG=1059717
NOTRY=true
CC=pasko@chromium.org,chrome-android-perf-status@chromium.org
TBR=crouleau@chromium.org

Change-Id: Id079ea6ce0c1df277218041a21b9a84828950ce9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2094126Reviewed-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@{#748172}

tools/perf/expectations.config

@@ -286,6 +286,7 @@ crbug.com/875878 [ android-nexus-6 android-webview ] rasterize_and_record_micro.
 crbug.com/948789 [ android-nexus-5 ] startup.mobile/maps_pwa:with_http_cache [ Skip ]
 crbug.com/948789 [ android-nexus-5x ] startup.mobile/maps_pwa:with_http_cache [ Skip ]
 crbug.com/1030735 [ android-weblayer ] startup.mobile/maps_pwa:with_http_cache [ Skip ]
+crbug.com/1059717 [ android-pixel-2 ] startup.mobile/maps_pwa:with_http_cache [ Skip ]
 
 # Benchmark: system_health.common_desktop
 crbug.com/903417 [ mac ] system_health.common_desktop/long_running:tools:gmail-foreground [ Skip ]