package/samba4: do not force target python

package/samba4: do not force target python

Samba does not need python on the target for file server functionality.
It does need it for the Active Directory Domain Controller feature,
which is already configured in buildroot as optional and already depends
on python3 since commit 4485a75859fbae99090b065ddd7c088a65571d37.

An unnecessary target python greatly increases the size of the target
filesystem. A somewhat minimal configuration with a samba server shunk
from an 82 MB rootfs to 53 MB with this patch.

Signed-off-by: Trent Piepho <trent.piepho@synapse.com>
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>