Currently, the router discovers initialization are done during startup.
If it were failed, the discovers are skipped. This is too strict, since
the initialization could be failed due to some requires services are not
ready when ctrld started, or router specific requirements for services
management during startup (like UnifiOS v4.0.20).
To fix this, ctrld should relax the initialization checking, allow it to
be failed, and still use the discovers later.