[Fix] Copy all install directories to proper system locations in Dockerfile

[Fix] Copy all install directories to proper system locations in Dockerfile

Fixed the issue where config files and other resources were not accessible
because we were copying install/* to /usr/* which put configs at /usr/etc
instead of /etc. Now explicitly copying:
- install/bin -> /usr/bin (binaries)
- install/lib -> /usr/lib (libraries)
- install/share -> /usr/share (plugins, rules, webui)
- install/etc -> /etc (configuration files)

This ensures rspamd can find all its files at standard system locations.