Missing Backup Folder in Client web Folder
## short description
The (manual) backup is not copied to the backup folder for download.
## correct behaviour
1, Manual Backup Start
2, backup download
3, The order /backup/ is missing in /client2/web8/
## environment
```
/var/www/clients/client2/web8/# ls -l
drwxr-xr-x 2 web8 client2 4096 May 15 10:16 cgi-bin
drwxr-xr-x 2 root root 4096 May 29 00:02 log
drwx--x--- 2 web8 client2 4096 May 15 10:16 private
drwxr-xr-x 2 root root 4096 May 29 09:34 ssl
drwxrwx--- 2 web8 client2 4096 May 29 11:16 tmp
drwxr-x--x 6 web8 client2 4096 May 29 10:00 web
```
```
ls /backup/web8/ -l
total 459776
-rw-rw---- 1 root root 1964276 May 29 11:26 manual-db_c2_ledoptix_2020-05-29_11-26.zip
-rw-rw---- 1 root root 471802001 May 29 11:26 manual-web8_2020-05-29_11-26.zip
```
```
nginx version: nginx/1.14.2
```
```
PHP 7.3.18-1+0~20200514.58+debian10~1.gbp12fa4f
```
## log entries
```
29.05.2020-11:33 - DEBUG - Remove Lock: /usr/local/ispconfig/server/temp/.ispconfig_lock
29.05.2020-11:34 - DEBUG - Calling function 'check_phpini_changes' from plugin 'webserver_plugin' raised by action 'server_plugins_loaded'.
29.05.2020-11:34 - DEBUG - Calling function 'backup_action' from plugin 'backup_plugin' raised by action 'backup_download'.
29.05.2020-11:34 - DEBUG - safe_exec cmd: mount 2>/dev/null | grep ' on /backup type ' - return code: 0
29.05.2020-11:34 - DEBUG - Remove Lock: /usr/local/ispconfig/server/temp/.ispconfig_lock
```
## Screenshot
issue