Change goma_mac_gtests' target mac dimensions to 10.13.

This will prevent the goma bots from running tests on 10.10, which is
being deprecated, and which appears to fail the tests anyway.

Change-Id: I17ed6c430e5ea3ee7b7eaa95fd6653038706fece
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2641146Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845744}

testing/buildbot/chromium.goma.fyi.json

@@ -15,7 +15,7 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "os": "Mac"
+              "os": "Mac-10.13"
             }
           ],
           "service_account": "chromium-tester@chops-service-accounts.iam.gserviceaccount.com"
@@ -32,7 +32,7 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "os": "Mac"
+              "os": "Mac-10.13"
             }
           ],
           "service_account": "chromium-tester@chops-service-accounts.iam.gserviceaccount.com"
@@ -56,7 +56,7 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "os": "Mac"
+              "os": "Mac-10.13"
             }
           ],
           "service_account": "chromium-tester@chops-service-accounts.iam.gserviceaccount.com"
@@ -73,7 +73,7 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "os": "Mac"
+              "os": "Mac-10.13"
             }
           ],
           "service_account": "chromium-tester@chops-service-accounts.iam.gserviceaccount.com"
@@ -301,7 +301,7 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "os": "Mac"
+              "os": "Mac-10.13"
             }
           ],
           "service_account": "chromium-tester@chops-service-accounts.iam.gserviceaccount.com"
@@ -318,7 +318,7 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "os": "Mac"
+              "os": "Mac-10.13"
             }
           ],
           "service_account": "chromium-tester@chops-service-accounts.iam.gserviceaccount.com"
@@ -342,7 +342,7 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "os": "Mac"
+              "os": "Mac-10.13"
             }
           ],
           "service_account": "chromium-tester@chops-service-accounts.iam.gserviceaccount.com"
@@ -359,7 +359,7 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "os": "Mac"
+              "os": "Mac-10.13"
             }
           ],
           "service_account": "chromium-tester@chops-service-accounts.iam.gserviceaccount.com"

testing/buildbot/test_suites.pyl

@@ -1687,7 +1687,7 @@
         'swarming': {
           'dimension_sets': [
             {
-              'os': 'Mac',
+              'os': 'Mac-10.13',
             },
           ],
         }
@@ -1696,7 +1696,7 @@
         'swarming': {
           'dimension_sets': [
             {
-              'os': 'Mac',
+              'os': 'Mac-10.13',
             },
           ],
         },