fix: clear proxy configs on boot

Unfortunately, Docker does not persist container IPs on boot, so containers may come up with the wrong IP, resulting in proxying to the incorrect app after a server restart. Instead, we should delete the configs and let ps:restore rebuild the proxy config correctly.

Closes #3932

plugins/nginx-vhosts/internal-functions

@@ -162,4 +162,5 @@ nginx_clear_config() {
   declare desc="Remove the nginx conf file"
   declare APP="$1"
   rm -f "$DOKKU_ROOT/$APP/nginx.conf"
+  fn-nginx-vhosts-nginx-init-cmd "reload"
 }