NameChangeUDPTest.roundTripTest sometimes fails

This time it happened on CentOS 8 distcheck.

https://jenkins.aws.isc.org/job/kea-dev/job/distcheck/414/execution/node/148/log/

23:38:28  [ RUN      ] NameChangeUDPTest.roundTripTest
23:38:28  ../../../../../../src/lib/dhcp_ddns/tests/ncr_udp_unittests.cc:1062: Failure
23:38:28  Value of: checkSendVsReceived(sent_ncrs_[i], received_ncrs_[i])
23:38:28    Actual: false
23:38:28  Expected: true
23:38:28  ../../../../../../src/lib/dhcp_ddns/tests/ncr_udp_unittests.cc:1062: Failure
23:38:28  Value of: checkSendVsReceived(sent_ncrs_[i], received_ncrs_[i])
23:38:28    Actual: false
23:38:28  Expected: true
23:38:28  [  FAILED  ] NameChangeUDPTest.roundTripTest (0 ms)