Decrease telemetry shards on chromeos-kevin-rel.

Most shards are quick enough that we can merge some:
https://ci.chromium.org/p/chromium/builders/ci/chromeos-kevin-rel/13179

This will help reduce load a little in the device pool.

R=jbudorick, martiniss

Bug: 989314
Change-Id: I4d6e07773ae2b9b9dabe76560501d38a5a8310cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1729956
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Auto-Submit: Ben Pastene <bpastene@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682964}

testing/buildbot/chromium.chromiumos.json

@@ -655,8 +655,7 @@
               "pool": "chrome-cros-dut"
             }
           ],
-          "idempotent": false,
-          "shards": 2
+          "idempotent": false
         },
         "trigger_script": {
           "script": "//testing/trigger_scripts/chromeos_device_trigger.py"
@@ -684,7 +683,7 @@
             }
           ],
           "idempotent": false,
-          "shards": 12
+          "shards": 10
         },
         "trigger_script": {
           "script": "//testing/trigger_scripts/chromeos_device_trigger.py"

testing/buildbot/test_suites.pyl

@@ -392,7 +392,6 @@
         ],
         'swarming': {
           'idempotent': False,  # https://crbug.com/549140
-          'shards': 2,
         },
       },
       'telemetry_unittests': {
@@ -404,7 +403,7 @@
         ],
         'swarming': {
           'idempotent': False,  # https://crbug.com/549140
-          'shards': 12,
+          'shards': 10,
         },
       },
     },