Avoid to use environment.

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

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\kill_processes.py"
     ],
     "name": "taskkill"
   },
   {
@@ skipping 303 matching lines @@
       "--gsutil-py-path",
       "RECIPE_PACKAGE_REPO[depot_tools]\\gsutil.py",
       "--ninja-path",
       "RECIPE_PACKAGE_REPO[depot_tools]\\ninja.exe",
       "--target",
       "Release",
       "--src-dir",
       "[BUILDER_CACHE]\\CrWinAsan\\src",
       "--goma-cache-dir",
       "[GOMA_CACHE]",
+      "--buildbot-buildername",
+      "CrWinAsan",
+      "--buildbot-mastername",
+      "chromium.fyi",
+      "--buildbot-slavename",
+      "TestSlavename",
       "--goma-deps-cache-dir",
       "[GOMA_DEPS_CACHE]",
       "--build-data-dir",
       "[ROOT]\\build_data_dir",
       "--compiler",
       "clang",
       "--",
       "browser_tests",
       "browser_tests_run",
       "chromium_builder_asan"
@@ skipping 92 matching lines @@
     "~followup_annotations": [
       "@@@STEP_TEXT@CrWinAsan tester@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]