Implement a connection timeout for JDBC. If it does not resolve in a timely, log a warn exception and stop

When JDBC connection is defined, it takes too long to start broker (from secs to minutes).
Similar issue was in AMQ6, but with starting the broker itself w/o JDBC.

To workaround this, one should use service rngd, which generates enough random numbers and results in a very quick connection to DB (via JDBC).

yum install rng-tools
systemctl start rngd

Start broker now.