Use platform path constant for SSSD log dir

The path to SSSD log directory is platform specific and should be in
ipaplatform module.

Reviewed-By: David Kupka <dkupka@redhat.com>

ipatests/test_integration/tasks.py

@@ -557,7 +557,7 @@ def setup_sssd_debugging(host):
                       paths.SSSD_CONF],
                      raiseonerr=False)
 
-    host.collect_log('/var/log/sssd/*')
+    host.collect_log(os.path.join(paths.VAR_LOG_SSSD_DIR, '*'))
 
     # Clear the cache and restart SSSD
     clear_sssd_cache(host)