[tools/perf] Re-enable system_health.memory_mobile in Nexus 5X

Fix was landed in:
https://chromium-review.googlesource.com/c/chromium/src/+/1691586

Keeps browse:social:tumblr_infinite_scroll:2018 disabled as
the story is constantly failing in CQ.

Bug: 970058
Bug: 1016701
Change-Id: Ifc128a5c00d00f04c9773f6be11bf9a145403d38
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1872057
Commit-Queue: Juan Antonio Navarro Pérez <perezju@chromium.org>
Reviewed-by: ssid <ssid@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708146}

tools/perf/expectations.config

@@ -385,11 +385,10 @@ crbug.com/923527 [ android-webview ] system_health.memory_mobile/load:media:soun
 crbug.com/947267 [ android-nexus-5x ] system_health.memory_mobile/background:media:imgur [ Skip ]
 crbug.com/954949 [ android-nexus-5x android-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/1016701 [ android-nexus-5x ] system_health.memory_mobile/browse:social:tumblr_infinite_scroll:2018 [ Skip ]
 crbug.com/1002640 [ android-pixel-2 ] system_health.memory_mobile/browse:chrome:newtab [ Skip ]
 crbug.com/1002665 [ android-pixel-2 ] system_health.memory_mobile/browse:chrome:omnibox [ Skip ]
 
-crbug.com/964960 [ android-nexus-5x ] system_health.memory_mobile/* [ 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 ]