GSS TSIG unit tests hang on CentOS 8 & Fedora 34

https://jenkins.aws.isc.org/job/kea-dev/job/ut-extended/432/execution/node/708/log/

15:00:44  [ RUN      ] GssTsigContextTest.sign
15:00:44  gss_tsig_context_unittests.cc:319: Failure
15:00:44  Expected: ret = key->getSecCtx().init(cred, srv_name, flags, intoken0, outtoken0, lifetime) doesn't throw an exception.
15:00:44    Actual: it throws.
15:00:44  [  FAILED  ] GssTsigContextTest.sign (2 ms)
15:00:44  [ RUN      ] GssTsigContextTest.signToWire
15:00:44  gss_tsig_context_unittests.cc:407: Failure
15:00:44  Expected: ret = key->getSecCtx().init(cred, srv_name, flags, intoken0, outtoken0, lifetime) doesn't throw an exception.
15:00:44    Actual: it throws.
15:00:44  [  FAILED  ] GssTsigContextTest.signToWire (1 ms)
15:00:44  [ RUN      ] GssTsigContextTest.signVerify
15:00:44  gss_tsig_context_unittests.cc:502: Failure
15:00:44  Expected: ret = key->getSecCtx().init(cred, srv_name, flags, intoken0, outtoken0, lifetime) doesn't throw an exception.
15:00:44    Actual: it throws.
15:00:44  [  FAILED  ] GssTsigContextTest.signVerify (1 ms)
15:00:44  [ RUN      ] GssTsigContextTest.signBadVerify
15:00:44  gss_tsig_context_unittests.cc:608: Failure
15:00:44  Expected: ret = key->getSecCtx().init(cred, srv_name, flags, intoken0, outtoken0, lifetime) doesn't throw an exception.
15:00:44    Actual: it throws.
15:00:44  [  FAILED  ] GssTsigContextTest.signBadVerify (1 ms)

15:00:44  [ RUN      ] TkeyExchangeTest.exchangeFail
15:00:44  tkey_exchange_unittests.cc:294: Failure
15:00:44  Expected: ex.doExchange(io_service) doesn't throw an exception.
15:00:44    Actual: it throws.
15:00:44  Google Test trace:
15:00:44  tkey_exchange_unittests.cc:287: timeout when DNS server is missing
<-- hang