Issue 49612 - lib389 remove_ds_instance() does not remove systemd units
Bug description: When running remove_ds_instance(), it does not remove
the systemd files that identify this instance.
Also, in previous DS versions, the /etc/dirsrv/slapd-INSTANCE
would have been moved to /etc/dirsrv/slapd-INSTANCE.removed.
This does not happen now.
Fix description: Change remove_ds_instance function so it disables systemd unit
and, in the result, it will remove symlinks. Also make the function
move the config_dir to config_dir.removed as remove-ds.pl does.
Add a basic test to src/lib389/lib389/tests/instance/remove_test.py
Fix local_simple_allocate, so it sets serverid properly.
https://pagure.io/389-ds-base/issue/49612
Reviewed by: mreynolds (Thanks!)