Log: libcrmcommon: lower watchdog messages when default

Previously, if a watchdog was left unconfigured by default, the log would be:

notice: check_sbd_timeout: Watchdog may be enabled but stonith-watchdog-timeout is disabled: (null)
info: check_sbd_timeout: Watchdog functionality is consistent: (null) delay exceeds timeout of -1ms

Now, a single debug message is printed in this case.