Disable system health smoke tests on Nexus5.

testing/buildbot/chromium.android.json

 {
   "Android Cronet Builder": {
     "additional_compile_targets": [
       "cronet_package"
     ]
   },
   "Android N5X Swarm Builder": {
     "gtest_tests": [
       {
         "override_compile_targets": [
@@ skipping 2407 matching lines @@
             }
           ]
         },
         "test": "unit_tests"
       }
     ],
     "isolated_scripts": [
       {
         "args": [
           "--browser=android-chromium",
-          "--device=android"
+          "--device=android",
+          "--skip=benchmarks.system_health_smoke_test.SystemHealthBenchmarkSmokeTest.*"
         ],
         "isolate_name": "telemetry_perf_unittests",
         "name": "telemetry_perf_unittests",
         "override_compile_targets": [
           "telemetry_perf_unittests"
         ],
         "swarming": {
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
@@ skipping 2765 matching lines @@
       },
       {
         "test": "chrome_sync_shell_test_apk"
       },
       {
         "test": "content_shell_test_apk"
       }
     ]
   }
 }