Set number of shards for telemetry_unittests to be 2

testing/buildbot/chromium.mac.json

Index: testing/buildbot/chromium.mac.json
diff --git a/testing/buildbot/chromium.mac.json b/testing/buildbot/chromium.mac.json
index 72133986d4833cad0abad91093f6131695d64d27..70adf7ee69da8704ed46cc48bab1c7d60cc5398d 100644
--- a/testing/buildbot/chromium.mac.json
+++ b/testing/buildbot/chromium.mac.json
@@ -371,7 +371,9 @@
           "telemetry_unittests_run"
         ],
         "swarming": {
-          "can_use_on_swarming_builders": true
+          "can_use_on_swarming_builders": true,
+          "hard_timeout": 960,
+          "shards": 2
         }
       }
     ]
@@ -722,7 +724,9 @@
           "telemetry_unittests_run"
         ],
         "swarming": {
-          "can_use_on_swarming_builders": true
+          "can_use_on_swarming_builders": true,
+          "hard_timeout": 960,
+          "shards": 2
         }
       }
     ]
@@ -1062,7 +1066,9 @@
           "telemetry_unittests_run"
         ],
         "swarming": {
-          "can_use_on_swarming_builders": true
+          "can_use_on_swarming_builders": true,
+          "hard_timeout": 960,
+          "shards": 2
         }
       }
     ]
@@ -1402,7 +1408,9 @@
           "telemetry_unittests_run"
         ],
         "swarming": {
-          "can_use_on_swarming_builders": true
+          "can_use_on_swarming_builders": true,
+          "hard_timeout": 960,
+          "shards": 2
         }
       }
     ]