BouncyCastle upgrade to 1.61 might cause flaky test issues

I've seen a lot of test timeout errors with QuorumSSL tests since I upgraded master to BouncyCastle 1.61 due to a Java 9 warning. The warning has been reported by eolivelli which we tried to solve by the upgrade, but the warning message is still present so I don't see any harm in downgrading to the previous version. 

The timeout errors are very frequent with recent Java versions (11+) and quite rare with Java 8.

I think it's worth a try to downgrade and see if tests will be in a better shape.