Disable parallelization on telemetry_unittests & set the number of sh…

…ards to 2 (linux)

It's a known problem that launching browsers in parallel on Linux will cause the
test to hang due to deadlock (
catapult-project/catapult#3074 (comment)),
and since each hang test takes 1 min timeout, so we disable telemetry
parallelization & shards it on 2 machines to reduce the overall wait time.

BUG=676742

Review-Url: https://codereview.chromium.org/2653163002
Cr-Commit-Position: refs/heads/master@{#445998}

testing/buildbot/chromium.fyi.json

@@ -10562,13 +10562,17 @@
         }
       },
       {
+        "args": [
+          "--jobs=1"
+        ],
         "isolate_name": "telemetry_unittests",
         "name": "telemetry_unittests",
         "override_compile_targets": [
           "telemetry_unittests_run"
         ],
         "swarming": {
-          "can_use_on_swarming_builders": true
+          "can_use_on_swarming_builders": true,
+          "shards": 2
         }
       }
     ],
@@ -11127,13 +11131,17 @@
         }
       },
       {
+        "args": [
+          "--jobs=1"
+        ],
         "isolate_name": "telemetry_unittests",
         "name": "telemetry_unittests",
         "override_compile_targets": [
           "telemetry_unittests_run"
         ],
         "swarming": {
-          "can_use_on_swarming_builders": true
+          "can_use_on_swarming_builders": true,
+          "shards": 2
         }
       }
     ],

testing/buildbot/chromium.linux.json

@@ -3249,13 +3249,17 @@
         }
       },
       {
+        "args": [
+          "--jobs=1"
+        ],
         "isolate_name": "telemetry_unittests",
         "name": "telemetry_unittests",
         "override_compile_targets": [
           "telemetry_unittests_run"
         ],
         "swarming": {
-          "can_use_on_swarming_builders": true
+          "can_use_on_swarming_builders": true,
+          "shards": 2
         }
       }
     ],
@@ -3804,13 +3808,17 @@
         }
       },
       {
+        "args": [
+          "--jobs=1"
+        ],
         "isolate_name": "telemetry_unittests",
         "name": "telemetry_unittests",
         "override_compile_targets": [
           "telemetry_unittests_run"
         ],
         "swarming": {
-          "can_use_on_swarming_builders": true
+          "can_use_on_swarming_builders": true,
+          "shards": 2
         }
       }
     ],
@@ -4165,13 +4173,17 @@
         }
       },
       {
+        "args": [
+          "--jobs=1"
+        ],
         "isolate_name": "telemetry_unittests",
         "name": "telemetry_unittests",
         "override_compile_targets": [
           "telemetry_unittests_run"
         ],
         "swarming": {
-          "can_use_on_swarming_builders": true
+          "can_use_on_swarming_builders": true,
+          "shards": 2
         }
       }
     ]