Disable swiftshader_unittests on some non-swarming GPU FYI mac bots

testing/buildbot/chromium.gpu.fyi.json

 {
   "AAAAA1 AUTOGENERATED FILE DO NOT EDIT": {},
   "AAAAA2 See generate_buildbot_json.py to make changes": {},
   "Android Release (NVIDIA Shield TV)": {
     "gtest_tests": [
       {
         "override_isolate_target": "angle_end2end_tests",
         "swarming": {
           "can_use_on_swarming_builders": false,
           "cipd_packages": [
@@ skipping 6187 matching lines @@
           "dimension_sets": [
             {
               "gpu": "1002:6821",
               "hidpi": "1",
               "os": "Mac"
             }
           ]
         },
         "test": "service_unittests",
         "use_xvfb": false
-      },
-      {
-        "swarming": {
-          "can_use_on_swarming_builders": false,
-          "dimension_sets": [
-            {
-              "gpu": "1002:6821",
-              "hidpi": "1",
-              "os": "Mac"
-            }
-          ]
-        },
-        "test": "swiftshader_unittests",
-        "use_xvfb": false
       }
     ],
     "isolated_scripts": [
       {
         "args": [
           "context_lost",
           "--show-stdout",
           "--browser=release",
           "-v",
           "--extra-browser-args=--enable-logging=stderr --js-flags=--expose-gc"
@@ skipping 412 matching lines @@
           "dimension_sets": [
             {
               "gpu": "10de:0fe9",
               "hidpi": "1",
               "os": "Mac"
             }
           ]
         },
         "test": "service_unittests",
         "use_xvfb": false
-      },
-      {
-        "swarming": {
-          "can_use_on_swarming_builders": false,
-          "dimension_sets": [
-            {
-              "gpu": "10de:0fe9",
-              "hidpi": "1",
-              "os": "Mac"
-            }
-          ]
-        },
-        "test": "swiftshader_unittests",
-        "use_xvfb": false
       }
     ],
     "isolated_scripts": [
       {
         "args": [
           "context_lost",
           "--show-stdout",
           "--browser=release",
           "-v",
           "--extra-browser-args=--enable-logging=stderr --js-flags=--expose-gc"
@@ skipping 1259 matching lines @@
           "can_use_on_swarming_builders": false,
           "dimension_sets": [
             {
               "gpu": "1002:679e",
               "os": "Mac-10.10"
             }
           ]
         },
         "test": "gles2_conform_test",
         "use_xvfb": false
-      },
-      {
-        "swarming": {
-          "can_use_on_swarming_builders": false,
-          "dimension_sets": [
-            {
-              "gpu": "1002:679e",
-              "os": "Mac-10.10"
-            }
-          ]
-        },
-        "test": "swiftshader_unittests",
-        "use_xvfb": false
       }
     ],
     "isolated_scripts": [
       {
         "args": [
           "context_lost",
           "--show-stdout",
           "--browser=release",
           "-v",
           "--extra-browser-args=--enable-logging=stderr --js-flags=--expose-gc"
@@ skipping 10432 matching lines @@
             {
               "gpu": "10de:104a",
               "os": "Windows-2008ServerR2-SP1"
             }
           ]
         }
       }
     ]
   }
 }