s4/selftest: Adjust samba4.blackbox.pkinit to use (s3) smbclient

s4/selftest: Adjust samba4.blackbox.pkinit to use (s3) smbclient

samba4.blackbox.pkinit falls to pass in environments that don't support
SMB2 because of use (s4) smbclient4. Change test to use (s3) smbclient

Additionally a test within the test script test_kinit_trusts_heimdal.sh
explicitly uses smbclient4 which can't negotiate SMB1 in environments
that don't support it. Add knownfail to cater for this & also remove entry
from the skip file

Further reference the smbclient4 specific test is associated with
https://bugzilla.samba.org/show_bug.cgi?id=12554 so maybe we should
keep it for the moment

Signed-off-by: Noel Power <noel.power@suse.com>
Reviewed-by: Ralph Boehme <slow@samba.org>