lib/param: Don't treat a missing include file as an error in handle_include().

lib/param: Don't treat a missing include file as an error in handle_include().

Same fix as in commit 09d7690

'samba-tool domain provision -d10' fails if the included file does not
exist:

lpcfg_load: refreshing parameters from /etc/samba/smb.conf
Processing section "[global]"
Can't find include file /etc/samba/usershares.conf
pm_process() returned No
ERROR: Unable to load default file
  File "/usr/lib64/python3.12/site-packages/samba/netcmd/domain/provision.py", line 183, in run
    lp = sambaopts.get_loadparm()
         ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.12/site-packages/samba/getopt.py", line 282, in get_loadparm
    self._lp.load_default()

Signed-off-by: Pavel Filipenský <pfilipensky@samba.org>
Reviewed-by: Martin Schwenke <martin@meltin.net>
Autobuild-User(master): Martin Schwenke <martins@samba.org>
Autobuild-Date(master): Wed Aug 21 00:04:19 UTC 2024 on atb-devel-224