refactor: Remove old unused stub asset script (#37967)

Should have been removed as part of
https://github.com/openedx/openedx-platform/issues/31604

xmodule/static_content.py

@@ -1,25 +0,0 @@
-# /usr/bin/env python
-"""
-This module used to hold a CLI utility for gathering up the JS and Sass used by several built-in XBlocks.
-
-It now remains as a stub, just for backwards compatibility.
-
-It will soon be removed as part of https://github.com/openedx/edx-platform/issues/31798.
-"""
-import logging
-import sys
-
-
-def main():
-    """
-    Warn that this script is now a stub, and return success (zero).
-    """
-    logging.warning(
-        "xmodule/static_content.py, aka xmodule_assets, is now a no-op. "
-        "Please remove calls to it from your build pipeline. It will soon be deleted.",
-    )
-    return 0
-
-
-if __name__ == "__main__":
-    sys.exit(main())