Issue 6041 - dscreate ds-root - accepts relative path (#6042)

Bug Description: When dscreate ds-root is invoked with a relative path to
root_dir, the relative path is written to defaults.inf, causing instance
creation failure.

Fix Description: Use abs path when writing root_dir to defaults.inf

Fixes: #6041

Reviewed by: @progier389, @droideck (Thank you)

src/lib389/lib389/cli_ctl/instance.py

@@ -234,7 +234,7 @@ def write(self, fout):
     PO = '{'
     PF = '}'
     copy_and_substitute('/usr/share/dirsrv/inf/defaults.inf', (
-            ('WORD', ' /', f' {args.root_dir}/'),
+            ('WORD', ' /', f' {os.path.abspath(args.root_dir)}/'),
             ('LINE', 'with_selinux', 'no'),
             ('LINE', 'with_systemd', '0'),
             ('LINE', 'user', user),