pyldb-samba: Use the same smb.conf variable name as the C wrapper users for LDB_FLG_N...

pyldb-samba: Use the same smb.conf variable name as the C wrapper users for LDB_FLG_NOSYNC

This was never noticed as most wrappers on make test run with TDB_NO_FSYNC

However ldb_mdb has not been told to use this (naturally) and so we rely
on the smb.conf setting to not force an fsync().

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13461

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>