unstable unit tests

The following tests failed irregularly in the past fortnight:

• AllocEngine6Test.reservedAddressInPoolReassignedOther https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1276/testReport/junit/(root)/AllocEngine6Test/all___debian_11_amd64___debian_11_amd64_results___reservedAddressInPoolReassignedOther/

  test_utils.cc:88
  Expected equality of these values:
    first->cltt_
      Which is: 1700075018
    second->cltt_
      Which is: 1700075019

• HttpClientTest.unreachable https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1273/testReport/junit/(root)/HttpClientTest/all___alpine_3_16_amd64___alpine_3_16_amd64_results___unreachable/

  server_client_unittests.cc:437
  Failed
  Timeout occurred while running the test!

• MemfileLeaseQueryImpl6ProcessTest.queryByClientIdActiveLeases https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1274/testReport/junit/(root)/MemfileLeaseQueryImpl6ProcessTest/all___debian_12_amd64___debian_12_amd64_results___queryByClientIdActiveLeases/

  lease_query_impl6_unittest.cc:1783
  Expected equality of these values:
    100
    cltt_opt->getValue()
      Which is: 101

• MySQLBulkLeaseQuery6ProcessTest.queryByClientIdActiveLeases https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1280/testReport/junit/(root)/MySQLBulkLeaseQuery6ProcessTest/all___freebsd_13_0_amd64___freebsd_13_0_amd64_results___queryByClientIdActiveLeases/

  bulk_lease_query6_unittest.cc:458
  Expected equality of these values:
    lease->valid_lft_ - elapsed
      Which is: 3500
    iaaddr_opt->getValid()
      Which is: 3499

• MySQLLeaseQueryImpl6ProcessTest.makeClientOptionSingleLink https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1265/testReport/junit/(root)/PgSQLLeaseQueryImpl6ProcessTest/all___alpine_3_15_amd64___alpine_3_15_amd64_results___makeClientOptionSingleLink/

  lease_query_impl6_unittest.cc:880
  Expected equality of these values:
    100
    cltt_opt->getValue()
      Which is: 101

• MySQLLeaseQueryImpl6ProcessTest.queryByClientIdActiveLeases https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1276/testReport/junit/(root)/MySQLLeaseQueryImpl6ProcessTest/all___debian_10_amd64___debian_10_amd64_results___queryByClientIdActiveLeases/

  lease_query_impl6_unittest.cc:1783
  Expected equality of these values:
    100
    cltt_opt->getValue()
      Which is: 101

• MySQLLeaseQueryImpl6ProcessTest.queryByIpAddressActiveLease https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1276/testReport/junit/(root)/MySQLLeaseQueryImpl6ProcessTest/all___ubuntu_20_04_amd64___ubuntu_20_04_amd64_results___queryByIpAddressActiveLease/

  lease_query_impl6_unittest.cc:1581
  Expected equality of these values:
    100
    cltt_opt->getValue()
      Which is: 101

• PgSQLBulkLeaseQuery6ProcessTest.queryByClientIdActiveLeases https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1275/testReport/junit/(root)/PgSQLBulkLeaseQuery6ProcessTest/all___fedora_38_amd64___fedora_38_amd64_results___queryByClientIdActiveLeases/

  bulk_lease_query6_unittest.cc:458
  Expected equality of these values:
    lease->valid_lft_ - elapsed
      Which is: 3500
    iaaddr_opt->getValid()
      Which is: 3499

• PgSQLLeaseQueryImpl6ProcessTest.makeClientOptionSingleLink https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1276/testReport/junit/(root)/PgSQLLeaseQueryImpl6ProcessTest/all___fedora_38_amd64___fedora_38_amd64_results___makeClientOptionSingleLink/

  lease_query_impl6_unittest.cc:880
  Expected equality of these values:
    100
    cltt_opt->getValue()
      Which is: 101

• PgSQLLeaseQueryImpl6ProcessTest.queryByIpAddressActiveLease https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/1270/testReport/junit/(root)/PgSQLLeaseQueryImpl6ProcessTest/all___rhel_9_amd64___rhel_9_amd64_results___queryByIpAddressActiveLease/

  lease_query_impl6_unittest.cc:1581
  Expected equality of these values:
    100
    cltt_opt->getValue()
      Which is: 101