chromium_tests: apply chromium.get_env() when running tests

scripts/slave/recipes/chromium_trybot.expected/process_dumps_failure.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\kill_processes.py"
     ],
     "name": "taskkill"
   },
   {
@@ skipping 413 matching lines @@
       "--build-dir",
       "[SLAVE_BUILD]\\src\\out",
       "--target",
       "Release",
       "--force-clean",
       "--config",
       "[SLAVE_BUILD]\\src\\chrome\\test\\mini_installer\\config\\config.config",
       "--write-full-results-to",
       "/path/to/tmp/json"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json"
+    },
     "name": "test_installer (with patch)"
   },
   {
     "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",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
       "@@@STEP_EXCEPTION@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]