chromium_tests: apply chromium.get_env() when running tests

scripts/slave/recipes/chromium.expected/full_chromium_win_Win8_Aura.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\kill_processes.py"
     ],
     "name": "taskkill"
   },
   {
@@ skipping 362 matching lines @@
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::isolate]\\resources\\find_isolated_tests.py",
       "--build-dir",
       "[SLAVE_BUILD]\\src\\out\\Release",
       "--output-json",
       "/path/to/tmp/json"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json"
+    },
     "name": "find isolated tests",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"dummy_target_1\": \"[dummy hash for dummy_target_1]\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"dummy_target_2\": \"[dummy hash for dummy_target_2]\"@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@",
       "@@@SET_BUILD_PROPERTY@swarm_hashes@{\"dummy_target_1\": \"[dummy hash for dummy_target_1]\", \"dummy_target_2\": \"[dummy hash for dummy_target_2]\"}@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport sys\nprint '*.isolated file for target %s is missing' % sys.argv[1]\nsys.exit(1)\n",
       "browser_tests"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json"
+    },
     "name": "[error] browser_tests",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import sys@@@",
       "@@@STEP_LOG_LINE@python.inline@print '*.isolated file for target %s is missing' % sys.argv[1]@@@",
       "@@@STEP_LOG_LINE@python.inline@sys.exit(1)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport sys\nprint '%s wasn\\'t triggered' % sys.argv[1]\nsys.exit(1)\n",
       "browser_tests"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json"
+    },
     "name": "[collect error] browser_tests",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import sys@@@",
       "@@@STEP_LOG_LINE@python.inline@print '%s wasn\\'t triggered' % sys.argv[1]@@@",
       "@@@STEP_LOG_LINE@python.inline@sys.exit(1)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\process_dumps.py",
       "--target",
       "Release"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json"
+    },
     "name": "process_dumps"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]