Issue 50164 - Add test for dscreate to basic test suite
Bug Description:
dscreate tests do not work properly when newer lib389 is used
with older 389-ds-base versions.
Fix Description:
* Unset PYTHONPATH for dscreate if it's set to prevent clobbering system
lib389.
* Don't run dscreate_test on older versions, where instance-specific sysconfig
env file is mentioned in systemd unit file. dscreate no longer creates it and
causes dirsrv service fail to start.
* Don't check for instance-specific sysconfig env file on removing the instance
since it's no longer created.
Fixes https://pagure.io/389-ds-base/issue/50164
Reviewed by: mreynolds (Thanks!)