message: Add default target to gn_isolate_map.pyl
  This is required to compile the default target in Android bots.
  Cr-Commit-Position: refs/heads/main@{#38830}
diff: "label": "//net/dcsctp:dcsctp_unittests",
  "type": "console_test_launcher",
  },
  + "default": {
  + "label": "//:default",
  + "type": "additional_compile_target",
  + },
  "android_instrumentation_test_apk": {
  "label": "//sdk/android:android_instrumentation_test_apk",
  "type": "console_test_launcher",
  