goma: use GOMA_SERVICE_ACCOUNT_JSON_FILE (reland #1)

scripts/slave/recipes/blink_downstream.expected/too_many_failures_for_retcode.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "client.v8.fyi",
       "--builder",
       "V8-Blink Linux 64",
@@ skipping 120 matching lines @@
       "--src-dir",
       "[SLAVE_BUILD]/src",
       "--goma-cache-dir",
       "[GOMA_CACHE]",
       "--build-tool",
       "ninja",
       "--compiler",
       "goma",
       "--goma-jsonstatus",
       "/path/to/tmp/json",
+      "--goma-service-account-json-file",
+      "/creds/service_accounts/service-account-goma-client.json",
       "--goma-dir",
       "[BUILD]/goma",
       "--",
       "blink_tests"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "compile",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output (invalid)@null@@@",
       "@@@STEP_LOG_END@json.output (invalid)@@@"
@@ skipping 206 matching lines @@
       "--src-dir",
       "[SLAVE_BUILD]/src",
       "--goma-cache-dir",
       "[GOMA_CACHE]",
       "--build-tool",
       "ninja",
       "--compiler",
       "goma",
       "--goma-jsonstatus",
       "/path/to/tmp/json",
+      "--goma-service-account-json-file",
+      "/creds/service_accounts/service-account-goma-client.json",
       "--goma-dir",
       "[BUILD]/goma",
       "--",
       "blink_tests"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "compile (2)",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output (invalid)@null@@@",
       "@@@STEP_LOG_END@json.output (invalid)@@@"
@@ skipping 60 matching lines @@
       "@@@STEP_TEXT@<br/>failures:<br/>bad/failing78.html<br/>bad/failing46.html<br/>bad/failing101.html<br/>bad/totally-bad-probably.html<br/>bad/failing70.html<br/>bad/failing17.html<br/>bad/failing82.html<br/>bad/failing120.html<br/>bad/failing73.html<br/>bad/failing112.html<br/>bad/failing114.html<br/>bad/failing99.html<br/>bad/failing121.html<br/>bad/failing108.html<br/>bad/failing76.html<br/>bad/failing50.html<br/>bad/failing23.html<br/>bad/failing104.html<br/>bad/failing93.html<br/>bad/failing67.html<br/>bad/failing124.html<br/>bad/failing53.html<br/>bad/failing69.html<br/>bad/failing117.html<br/>bad/failing34.html<br/>bad/failing51.html<br/>bad/failing80.html<br/>bad/failing20.html<br/>bad/failing107.html<br/>bad/failing56.html<br/>bad/failing68.html<br/>bad/failing71.html<br/>bad/failing77.html<br/>bad/failing39.html<br/>bad/failing92.html<br/>bad/failing90.html<br/>bad/failing89.html<br/>bad/failing122.html<br/>bad/failing105.html<br/>tricky/totally-maybe-not-awesome.html<br/>bad/failing36.html<br/>bad/failing44.html<br/>bad/failing21.html<br/>bad/failing85.html<br/>bad/failing42.html<br/>bad/failing55.html<br/>bad/failing9.html<br/>bad/failing15.html<br/>bad/failing65.html<br/>bad/failing118.html<br/>bad/failing95.html<br/>bad/failing45.html<br/>bad/failing66.html<br/>bad/failing26.html<br/>bad/failing35.html<br/>bad/failing74.html<br/>bad/failing109.html<br/>bad/failing97.html<br/>bad/failing58.html<br/>bad/failing37.html<br/>bad/failing11.html<br/>bad/failing111.html<br/>bad/failing86.html<br/>bad/failing30.html<br/>bad/failing54.html<br/>bad/failing38.html<br/>bad/failing13.html<br/>bad/failing63.html<br/>bad/failing116.html<br/>bad/failing41.html<br/>bad/failing18.html<br/>bad/failing84.html<br/>bad/failing2.html<br/>bad/failing28.html<br/>bad/failing33.html<br/>bad/failing106.html<br/>bad/failing48.html<br/>bad/failing0.html<br/>bad/failing4.html<br/>bad/failing64.html<br/>bad/failing47.html<br/>bad/failing27.html<br/>bad/failing25.html<br/>bad/failing8.html<br/>bad/failing100.html<br/>bad/failing102.html<br/>bad/failing123.html<br/>bad/failing88.html<br/>bad/failing61.html<br/>bad/failing79.html<br/>bad/failing43.html<br/>bad/failing57.html<br/>bad/failing16.html<br/>bad/failing96.html<br/>bad/failing94.html<br/>bad/failing119.html<br/>bad/failing113.html<br/>bad/failing72.html<br/>bad/failing1.html<br/>bad/failing103.html<br/>bad/failing110.html<br/>bad/failing32.html<br/>bad/failing12.html<br/>bad/failing10.html<br/>bad/failing40.html<br/>bad/failing5.html<br/>bad/failing75.html<br/>bad/failing98.html<br/>bad/failing115.html<br/>bad/failing49.html<br/>bad/failing6.html<br/>bad/failing19.html<br/>bad/failing87.html<br/>bad/failing59.html<br/>bad/failing22.html<br/>bad/failing24.html<br/>bad/failing3.html<br/>bad/failing91.html<br/>bad/failing60.html<br/>bad/failing81.html<br/>bad/failing83.html<br/>bad/failing62.html<br/>bad/failing52.html<br/>bad/failing29.html<br/>bad/failing31.html<br/>bad/failing7.html<br/>bad/failing14.html<br/>@@@",
       "@@@STEP_FAILURE@@@"
     ]
   },
   {
     "name": "$result",
     "reason": "1 out of 1 aggregated steps failed. Failures: Step('webkit_tests (retry summary)') failed with return_code 1",
     "status_code": 1
   }
 ]