Double Builds for Blimp Integration Test Infrastructure on FYI bot

scripts/slave/recipes/chromium_pgo.expected/full_tryserver_chromium_win_win_pgo.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\kill_processes.py"
     ],
     "name": "taskkill"
   },
   {
@@ skipping 141 matching lines @@
       "-u",
       "[SLAVE_BUILD]\\src\\tools\\mb\\mb.py",
       "gen",
       "-m",
       "tryserver.chromium.win",
       "-b",
       "win_pgo",
       "--config-file",
       "[SLAVE_BUILD]\\src\\tools\\mb\\mb_config.pyl",
       "--phase",
-      "1",
+      "pgo_phase_1",
       "//out/Release"
     ],
     "cwd": "[SLAVE_BUILD]\\src",
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json",
       "GYP_MSVS_VERSION": "2015"
     },
     "name": "generate_build_files"
   },
   {
@@ skipping 503 matching lines @@
       "-u",
       "[SLAVE_BUILD]\\src\\tools\\mb\\mb.py",
       "gen",
       "-m",
       "tryserver.chromium.win",
       "-b",
       "win_pgo",
       "--config-file",
       "[SLAVE_BUILD]\\src\\tools\\mb\\mb_config.pyl",
       "--phase",
-      "2",
+      "pgo_phase_2",
       "//out/Release"
     ],
     "cwd": "[SLAVE_BUILD]\\src",
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json",
       "GYP_MSVS_VERSION": "2015"
     },
     "name": "generate_build_files (2)"
   },
   {
@@ skipping 55 matching lines @@
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"branch\": \"\", \"buildername\": \"win_pgo\", \"buildnumber\": 571, \"issue\": 12853011, \"mastername\": \"tryserver.chromium.win\", \"patch_project\": \"chromium\", \"patchset\": 1, \"project\": \"chrome\", \"recipe\": \"chromium_pgo\", \"repository\": \"\", \"requester\": \"commit-bot@chromium.org\", \"revision\": \"HEAD\", \"rietveld\": \"https://codereview.chromium.org\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}"
     ],
     "name": "package build"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]