Revert "Re-enabled system_health.memory_mobile benchmarks"

This reverts commit e61604f9.

Reason for revert: Tests started failing again.

Original change's description:
> Re-enabled system_health.memory_mobile benchmarks
> 
> These should be working again after
> https://chromium-review.googlesource.com/c/chromium/src/+/1626991
> 
> TBR=perezju@chromium.org
> 
> Bug: 964804
> Change-Id: Iddbffc36717e86db4da46cfc733821f169cf6f38
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1628317
> Reviewed-by: oysteine <oysteine@chromium.org>
> Commit-Queue: oysteine <oysteine@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#663183}

TBR=oysteine@chromium.org,perezju@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 964804
Change-Id: I23caa9852a521316ec7b61369584daa45e146ff9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1630225Reviewed-by: Sebastien Lalancette <seblalancette@chromium.org>
Commit-Queue: Sebastien Lalancette <seblalancette@chromium.org>
Cr-Commit-Position: refs/heads/master@{#663933}

tools/perf/expectations.config

@@ -326,6 +326,29 @@ crbug.com/947267 [ Nexus_5X ] system_health.memory_mobile/background:media:imgur
 crbug.com/954949 [ Nexus5X_Webview ] system_health.memory_mobile/browse:news:washingtonpost [ Skip ]
 crbug.com/961417 [ Android_Go ] system_health.memory_mobile/browse:social:tumblr_infinite_scroll:2018 [ Skip ]
 
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/browse:media:flickr_infinite_scroll [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/browse:search:amp:2018 [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:games:lazors [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:games:spychase:2018 [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:media:flickr:2018 [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:news:irctc [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:search:baidu:2018 [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:search:google:2018 [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:tools:stackoverflow:2018 [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/background:search:google [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/browse:media:googleplaystore:2019 [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/browse:media:imgur [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/browse:media:facebook_photos [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/browse:media:youtube [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/browse:shopping:lazada [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/browse:tools:maps [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:media:dailymotion [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:news:qq [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:news:wikipedia:2018 [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:search:ebay:2018 [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:search:taobao [ Skip ]
+crbug.com/964804 [ Nexus_5X ] system_health.memory_mobile/load:tools:dropbox [ Skip ]
+
 # Benchmark: tab_switching.typical_25
 crbug.com/747026 [ Mac ] tab_switching.typical_25/multitab:misc:typical24 [ Skip ]
 crbug.com/883731 [ Win ] tab_switching.typical_25/multitab:misc:typical24 [ Skip ]