chore: drop package-based bash-completion priming

This is now down in the plugin:install step.

debian/postinst

@@ -80,9 +80,6 @@ case "$1" in
     echo "Install all core plugins"
     dokku plugin:install --core
 
-    echo "Creating bash-completion cache"
-    dokku --quiet help --all | awk '/^    /{ print $1 }' | sort > "/var/cache/dokku-completion"
-
     rm -f ${DOKKU_ROOT}/VERSION
     cp ${DOKKU_LIB_ROOT}/STABLE_VERSION ${DOKKU_ROOT}/VERSION
 

rpm/dokku.postinst

@@ -37,9 +37,6 @@ setup-plugins() {
 
   echo "Install all core plugins"
   dokku plugin:install --core
-
-  echo "Creating bash-completion cache"
-  dokku --quiet help --all | awk '/^    /{ print $1 }' | sort > "/var/cache/dokku-completion"
 }
 
 setup-sshcommand() {