Not supported jdk/net testcases in jdk20 on aix

Following tests got error message `java.lang.UnsupportedOperationException: Unimplemented on AIX`

[java/net/vthread/HttpALot.java.HttpALot](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/java_net_vthread_HttpALot/java/HttpALot/)
[java/net/vthread/HttpALot.java.HttpALot](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/java_net_vthread_HttpALot/java/HttpALot_2/)
[java/net/vthread/InterruptHttp.java.InterruptHttp](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/java_net_vthread_InterruptHttp/java/InterruptHttp/)
[java/net/vthread/InterruptHttp.java.InterruptHttp](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/java_net_vthread_InterruptHttp/java/InterruptHttp_2/)
[jdk/net/ExtendedSocketOption/DontFragmentTest.java.DontFragmentTest](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/jdk_net_ExtendedSocketOption_DontFragmentTest/java/DontFragmentTest/)
[jdk/net/ExtendedSocketOption/DontFragmentTest.java.DontFragmentTest](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/jdk_net_ExtendedSocketOption_DontFragmentTest/java/DontFragmentTest_2/)
[java/net/vthread/BlockingSocketOps.java#direct-register.BlockingSocketOps_direct-register](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/java_net_vthread_BlockingSocketOps/java_direct-register/BlockingSocketOps_direct_register/)
[java/net/vthread/BlockingSocketOps.java#direct-register.BlockingSocketOps_direct-register](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/java_net_vthread_BlockingSocketOps/java_direct-register/BlockingSocketOps_direct_register_2/)
[java/net/vthread/BlockingSocketOps.java#default.BlockingSocketOps_default](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/java_net_vthread_BlockingSocketOps/java_default/BlockingSocketOps_default/)
[java/net/vthread/BlockingSocketOps.java#default.BlockingSocketOps_default](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_0/20/testReport/junit/java_net_vthread_BlockingSocketOps/java_default/BlockingSocketOps_default_2/)
[java/nio/channels/vthread/BlockingChannelOps.java#default.BlockingChannelOps_default](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_1/20/testReport/junit/java_nio_channels_vthread_BlockingChannelOps/java_default/BlockingChannelOps_default/)
[java/nio/channels/vthread/BlockingChannelOps.java#default.BlockingChannelOps_default](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_1/20/testReport/junit/java_nio_channels_vthread_BlockingChannelOps/java_default/BlockingChannelOps_default_2/)
[java/nio/channels/vthread/BlockingChannelOps.java#direct-register.BlockingChannelOps_direct-register](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_1/20/testReport/junit/java_nio_channels_vthread_BlockingChannelOps/java_direct-register/BlockingChannelOps_direct_register/)
[java/nio/channels/vthread/BlockingChannelOps.java#direct-register.BlockingChannelOps_direct-register](https://ci.adoptium.net/job/Test_openjdk20_hs_extended.openjdk_ppc64_aix_testList_1/20/testReport/junit/java_nio_channels_vthread_BlockingChannelOps/java_direct-register/BlockingChannelOps_direct_register_2/)

Start with the linked CI reports for HttpALot.java, InterruptHttp.java, DontFragmentTest.java, BlockingSocketOps.java, and BlockingChannelOps.java, confirming the repeated UnsupportedOperationException on AIX. Trace each test's AIX-specific behavior and determine the appropriate handling for these unsupported cases. Done means the affected AIX test runs no longer report these failures.

Written by the indexing model from the issue text.