Check slapadd result before continuing with test

tests/scripts/lloadd/test001-backend-issues

tests/scripts/lloadd/test002-load

tests/scripts/lloadd/test003-cnconfig

tests/scripts/lloadd/test004-monitor

tests/scripts/lloadd/test007-coherence

tests/scripts/test049-sync-config

tests/scripts/test050-syncrepl-multiprovider

tests/scripts/test053-syncprov-glue

tests/scripts/test058-syncrepl-asymmetric

tests/scripts/test059-consumer-config

tests/scripts/test061-syncreplication-initiation

tests/scripts/test062-config-delete

tests/scripts/test063-delta-multiprovider

tests/scripts/test064-constraint

tests/scripts/test066-autoca

tests/scripts/test069-delta-multiprovider-starttls

tests/scripts/test070-delta-multiprovider-ldaps

tests/scripts/test071-dirsync

tests/scripts/test076-authid-rewrite

tests/scripts/test078-persistent-sessionlog