Ipv6 tests still fail on Aix machines

Some ipv6 tests continue to fail on all of our aix machines. The tests being:

java/net/DatagramSocket/DatagramSocketExample.java.DatagramSocketExample
java/net/DatagramSocket/DatagramSocketMulticasting.java.DatagramSocketMulticasting
java/net/MulticastSocket/SetOutgoingIf.java.SetOutgoingIf
java/net/MulticastSocket/JoinLeave.java.JoinLeave
java/net/MulticastSocket/Promiscuous.java.Promiscuous
java/nio/channels/DatagramChannel/AdaptorMulticasting.java.AdaptorMulticasting

Fail with
```
19:47:42 STDOUT:
19:47:42 Test family=INET, multicast group=/225.4.5.6, interface=en1
19:47:42 STDERR:
19:47:42 java.lang.IllegalArgumentException: IPv6 socket cannot join IPv4 multicast group
19:47:42 at java.base/sun.nio.ch.DatagramChannelImpl.innerJoin(DatagramChannelImpl.java:1473)
```
It is known upstream that these tests will fail if ipv6 is not correctly configured https://bugs.openjdk.java.net/browse/JDK-8278122

These tests belong to the jdk_net test target. Most recent failure was during the jdk18+36 release https://ci.adoptopenjdk.net/job/Test_openjdk18_hs_extended.openjdk_ppc64_aix_testList_0/24/testReport/

Start by reproducing the six listed IPv6 tests in the jdk_net test target on an AIX machine, using the linked CI report as the failure reference. Read the upstream JDK-8278122 context and inspect the AIX IPv6 configuration relevant to the failing multicast joins. Done means the affected tests pass on the AIX machines or the required configuration limitation is documented.

Written by the indexing model from the issue text.