crimson/monc: unify handling auth_service_ticket_ttl with classical OSD

crimson/monc: unify handling auth_service_ticket_ttl with classical OSD

In the classical `MonClient` the `auth_service_ticket_ttl` is lower
bounded to `30` units.

```cpp
  utime_t now = ceph_clock_now();
  utime_t cutoff = now;
  cutoff -= std::min(30.0, cct->_conf->auth_service_ticket_ttl / 4.0);
  utime_t issued_at_lower_bound = now;
  issued_at_lower_bound -= cct->_conf->auth_service_ticket_ttl;
  if (!rotating_secrets->need_new_secrets(cutoff)) {
    ldout(cct, 10) << "_check_auth_rotating have uptodate secrets (they expire after " << cutoff << ")" << dendl;
    rotating_secrets->dump_rotating();
    return 0;
  }
```

The unification affects also the debug mesages.

Signed-off-by: Radoslaw Zarzynski <rzarzyns@redhat.com>