[telemetry] Disable system health key mobile sites benchmark on Android
[telemetry] Disable system health key mobile sites benchmark on Android

This test is failing on many of the Android bots (both reference and
ToT).

TBR=nednguyen@google.com
BUG=601953
CQ_EXTRA_TRYBOTS=tryserver.chromium.perf:android_s5_perf_cq;tryserver.chromium.perf:winx64_10_perf_cq;tryserver.chromium.perf:linux_perf_cq

Review URL: https://codereview.chromium.org/1869383005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#386314}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk