sun/security/krb5/auto/UserIterCount.java fails on Linux platforms/versions with javax.security.auth.login.LoginException

This failure is seen across Linux platforms during JDK17 April release triage and is reported in JBS as https://bugs.openjdk.org/browse/JDK-8382876

```
18:37:07 STDERR:
18:37:07 javax.security.auth.login.LoginException: Receive timed out
18:37:07 at jdk.security.auth/com.sun.security.auth.module.Krb5LoginModule.attemptAuthentication(Krb5LoginModule.java:789)
18:37:07 at jdk.security.auth/com.sun.security.auth.module.Krb5LoginModule.login(Krb5LoginModule.java:597)
18:37:07 at Context.fromUserPass(Context.java:190)
18:37:07 at Context.fromUserPass(Context.java:147)
18:37:07 at UserIterCount.main(UserIterCount.java:59)
18:37:07 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
18:37:07 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
18:37:07 at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
18:37:07 at java.base/java.lang.reflect.Method.invoke(Method.java:569)
18:37:07 at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
18:37:07 at java.base/java.lang.Thread.run(Thread.java:840)
18:37:07 Caused by: java.net.SocketTimeoutException: Receive timed out
18:37:07 at java.base/sun.nio.ch.DatagramChannelImpl.trustedBlockingReceive(DatagramChannelImpl.java:703)
18:37:07 at java.base/sun.nio.ch.DatagramChannelImpl.blockingReceive(DatagramChannelImpl.java:633)
18:37:07 at java.base/sun.nio.ch.DatagramSocketAdaptor.receive(DatagramSocketAdaptor.java:240)
18:37:07 at java.base/java.net.DatagramSocket.receive(DatagramSocket.java:700)
18:37:07 at java.security.jgss/sun.security.krb5.internal.UDPClient.receive(NetClient.java:205)
18:37:07 at java.security.jgss/sun.security.krb5.KdcComm$KdcCommunication.run(KdcComm.java:409)
18:37:07 at java.security.jgss/sun.security.krb5.KdcComm$KdcCommunication.run(KdcComm.java:369)
18:37:07 at java.base/java.security.AccessController.doPrivileged(AccessController.java:569)
18:37:07 at java.security.jgss/sun.security.krb5.KdcComm.send(KdcComm.java:353)
18:37:07 at java.security.jgss/sun.security.krb5.KdcComm.sendIfPossible(KdcComm.java:252)
18:37:07 at java.security.jgss/sun.security.krb5.KdcComm.send(KdcComm.java:228)
18:37:07 at java.security.jgss/sun.security.krb5.KdcComm.send(KdcComm.java:199)
18:37:07 at java.security.jgss/sun.security.krb5.KrbAsReqBuilder.send(KrbAsReqBuilder.java:345)
18:37:07 at java.security.jgss/sun.security.krb5.KrbAsReqBuilder.action(KrbAsReqBuilder.java:498)
18:37:07 at jdk.security.auth/com.sun.security.auth.module.Krb5LoginModule.attemptAuthentication(Krb5LoginModule.java:751)
18:37:07 ... 10 more
18:37:07
18:37:07 JavaTest Message: Test threw exception: javax.security.auth.login.LoginException: Receive timed out
18:37:07 JavaTest Message: shutting down test
```

Seems it may be intermittent, or failing on some nodes and not others:
- For x64 Linux, https://github.com/adoptium/aqa-tests/issues/7056#issuecomment-4295856322 the test fails on dynamic nodes, but can pass on one of the static nodes (test-azure-ubuntu2404-x64-1).
- passes on aarch64_linux on test-docker-ubuntu2404-armv8-5, example https://ci.adoptium.net/job/Test_openjdk17_hs_sanity.openjdk_aarch64_linux_testList_1/66/testReport/sun_security_krb5_auto_UserIterCount/

Needs more investigation, but seems to pass when rerun on ubuntu2024 nodes

Start with sun/security/krb5/auto/UserIterCount.java and reproduce the failure on the reported Linux nodes, comparing dynamic and static Ubuntu 24.04 environments. Review the linked test reports and Kerberos timeout behavior; done means identifying the platform-dependent cause and making the test reliably pass across the affected nodes.

Written by the indexing model from the issue text.