Eventscripts: split 50.samba into 49.winbind and 50.samba

Eventscripts: split 50.samba into 49.winbind and 50.samba

winbind and samba can be separately managed.  This makes the service
starting and stopping code way too complicated, and even adds a small
amount of complexity to the monitoring code.  The sensible option is
to split this eventscript in two.

There are two potentially backward incompatible changes here:

* Functionality has been removed that allowed 50.samba to manage
  winbind when CTDB_MANAGES_WINBIND was unset but the smb.conf
  "security" parameter was set to "ADS" or "DOMAIN".

  Maintaining this functionality would have required moving the
  testparm-related code to the functions file, deciding where the
  cache file should go, and then calling it from both 49.winbind and
  50.samba.  This feature wasn't of great value and asking
  administrators to set an extra variable in exchange for code
  simplicity seems like a reasonable deal.

* External code will need to be changed if it calls 50.samba directly
  with winbind-related expectations.  This is fairly obvious!

Signed-off-by: Martin Schwenke <martin@meltin.net>