fix: second round audit - backup paths, cleanup, dead code

CT scripts:
- ct/hoodik.sh: backup to /opt instead of /tmp
- ct/pixelfed.sh: backup to /opt, add CLEAN_INSTALL=1
- ct/skylite-ux.sh: backup to /opt instead of /tmp

Install scripts:
- install/alpine-install.sh: add missing cleanup_lxc
- install/ubuntu-install.sh: replace manual apt-get cleanup with cleanup_lxc
- install/debian-install.sh: apt-get -> apt
- install/hoodik-install.sh: remove 40 lines of dead commented code
- install/step-ca-install.sh: remove  from export builtins

install/alpine-install.sh

@@ -23,3 +23,4 @@ msg_ok "Installed Dependencies"
 
 motd_ssh
 customize
+cleanup_lxc