fix: optimize certbot ownership script to reduce container startup time

[addievo]

Replace inefficient find/execdir implementation that was causing 3+ minute startup delays with a more efficient approach that:

1. Uses a flag file to skip redundant operations on container restarts
2. Processes site-packages directories with bulk chown operations instead of individual file checks and changes
3. Maintains the same functionality while dramatically improving performance

This change should significantly reduce container startup time while ensuring all necessary file permissions are still properly set.

[nginxproxymanagerci]

Docker Image for build 1 is available on
DockerHub
as nginxproxymanager/nginx-proxy-manager-dev:pr-4491

Note: ensure you backup your NPM instance before testing this image! Especially if there are database changes
Note: this is a different docker image namespace than the official image