chromium_tests: apply chromium.get_env() when running tests

scripts/slave/recipes/findit/chromium/test.expected/none_swarming_tests.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\kill_processes.py"
     ],
     "name": "taskkill"
   },
   {
@@ skipping 588 matching lines @@
       "/path/to/tmp/json",
       "--generate-json-file",
       "-o",
       "gtest-results/gl_tests.exe",
       "--builder-name=win_chromium_variable",
       "--slave-name=build1-a1",
       "--build-number=1",
       "gl_tests.exe",
       "Test.One\nTest.Two\nTest.Three"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json"
+    },
     "name": "test r1.gl_tests (r1)",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@1@@@",
       "step returned non-zero exit code: 1",
       "@@@STEP_TEXT@<br/>failures:<br/>Test.One<br/>Test.Two<br/>@@@",
       "@@@STEP_FAILURE@@@"
     ]
   },
   {
     "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": "test r1.process_dumps",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@1@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "import sys; sys.exit(0)"
@@ skipping 26 matching lines @@
       "@@@STEP_LOG_END@report@@@",
       "@@@SET_BUILD_PROPERTY@report@{\"culprits\": {\"gl_tests\": {\"Test.One\": \"r1\", \"Test.Two\": \"r1\"}}, \"metadata\": {\"regression_range_size\": 1}, \"result\": {\"r1\": {\"gl_tests\": {\"failures\": [\"Test.One\", \"Test.Two\"], \"status\": \"failed\", \"valid\": true}}}}@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]