Fix name in description of 'create_cipd_packages.sh' (flutter#44513)

The description uses an old name.

This PR also partly exists to spread awareness that this script exists, for whenever we need to upload [android versions to CIPD](https://chrome-infra-packages.appspot.com/p/flutter/android/sdk/all/mac-arm64/+/).

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

tools/android_sdk/create_cipd_packages.sh

@@ -4,12 +4,12 @@
 
 print_usage () {
   echo "Usage:"
-  echo "  ./create_cipd_united_package.sh <VERSION_TAG> [PATH_TO_SDK_DIR]"
+  echo "  ./create_cipd_packages.sh <VERSION_TAG> [PATH_TO_SDK_DIR]"
   echo "    Downloads, packages, and uploads Android SDK packages where:"
   echo "      - VERSION_TAG is the tag of the cipd packages, e.g. 28r6 or 31v1"
   echo "      - PATH_TO_SDK_DIR is the path to the sdk folder. If omitted, this defaults to"
   echo "                      your ANDROID_SDK_ROOT environment variable."
-  echo "  ./create_cipd_united_package.sh list"
+  echo "  ./create_cipd_packages.sh list"
   echo "    Lists the available packages for use in 'packages.txt'"
   echo ""
   echo "This script downloads the packages specified in packages.txt and uploads"