[benchmarking] disable browse:social:pinterest_infinite_scroll:2019 on pixel 4a

Use the new tag to disable the failing test on pixel 4a.

Bug: chromium:1162969
Change-Id: Iaf802cd5450cfe69ae217f3f473b1dc2aa860617
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2610352
Auto-Submit: Wenbin Zhang <wenbinzhang@google.com>
Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840265}

tools/perf/expectations.config

@@ -5,7 +5,7 @@
 #         sierra highsierra android-marshmallow android-lollipop android-nougat android-oreo android-pie android-10
 #         android-kitkat ubuntu fuchsia ]
 # tags: [ android-go android-low-end android-nexus-5 android-nexus-5x android-nexus-6
-#         android-pixel-2 desktop mobile ]
+#         android-pixel-2 desktop mobile android-pixel-4a ]
 # tags: [ android-not-webview android-webview android-webview-google android-chromium
 #         reference release debug exact release-x64 debug-x64 android-weblayer ]
 # results: [ Skip ]
@@ -191,6 +191,9 @@ crbug.com/1095610 [ win-laptop ] media.desktop/video.html?src=garden2_10s.mp4&se
 crbug.com/1036360 [ win7 ] power.desktop/abcnews [ Skip ]
 crbug.com/1082094 [ win10 ] power.desktop/abcnews [ Skip ]
 
+# Benchmark: power.desktop
+crbug.com/1162969 [ android-pixel-4a ] power.mobile/browse:social:pinterest_infinite_scroll:2019 [ Skip ]
+
 # Benchmark: rendering.desktop
 crbug.com/755556 [ mac ] rendering.desktop/mix_blend_mode_animation_difference [ Skip ]
 crbug.com/755556 [ mac ] rendering.desktop/mix_blend_mode_animation_hue [ Skip ]