python/samba: ignore encoding errors while reading files

Provisioning fails on C locale due to the Unicode quotes in ldif
data. Patch read_and_sub_file() to read the files as UTF-8.
23 jobs for phgsng-ldif-encoding in 53 minutes and 5 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Build
passed #176592588
docker shared
ctdb

00:43:04

passed #176592568
docker shared
others

00:12:13

passed #176592569
docker shared
samba

00:20:31

passed #176592598
docker private
samba-ad-dc-1

00:53:04

passed #176592579
docker shared
samba-ad-dc-2

00:47:37

passed #176592580
docker shared
samba-ad-dc-3

00:37:36

passed #176592581
docker shared
samba-ad-dc-4

00:44:53

passed #176592582
docker shared
samba-ad-dc-5

00:38:46

passed #176592583
docker shared
samba-ad-dc-6

00:37:02

passed #176592584
docker shared
samba-ad-dc-backup

00:39:23

passed #176592592
docker shared
samba-ad-dc-ntvfs

00:34:54

passed #176592578
docker shared
samba-ad-member

00:22:15

passed #176592589
docker shared
samba-ctdb

00:18:38

passed #176592595
docker private
samba-fileserver

00:28:57

passed #176592586
docker shared
samba-libs

00:32:50

passed #176592572
docker shared
samba-none-env

00:47:26

passed #176592573
docker shared
samba-nopython

00:29:57

passed #176592574
docker shared
samba-nopython-py2

00:36:30

passed #176592599
docker private
samba-nt4

00:45:23

passed #176592577
docker shared
samba-o3

00:32:26

passed #176592587
docker shared
samba-static

00:44:36

passed #176592575
docker shared
samba-systemkrb5

00:14:32

passed #176592576
docker shared
samba-xc

00:04:46