Update ProblemList_openjdk21-openj9.txt to add the link to a new issue

Added link to https://github.ibm.com/runtimes/backlog/issues/1591 for java/net/MulticastSocket/Promiscuous.java because of failures in linux-s390x and aix-all platforms

openjdk/excludes/ProblemList_openjdk21-openj9.txt

@@ -226,7 +226,7 @@ java/net/InetAddress/InternalNameServiceWithHostsFileTest.java https://github.co
 java/net/MulticastSocket/B6427403.java https://github.ibm.com/runtimes/backlog/issues/715 macosx-all,aix-all
 java/net/MulticastSocket/MulticastAddresses.java https://github.ibm.com/runtimes/backlog/issues/715 macosx-all
 java/net/MulticastSocket/NoSetNetworkInterface.java https://github.ibm.com/runtimes/backlog/issues/655 windows-all
-java/net/MulticastSocket/Promiscuous.java https://github.com/adoptium/infrastructure/issues/699 linux-s390x,aix-all
+java/net/MulticastSocket/Promiscuous.java https://github.ibm.com/runtimes/backlog/issues/1591 linux-s390x,aix-all
 java/net/MulticastSocket/PromiscuousIPv6.java https://github.com/adoptium/infrastructure/issues/699 linux-s390x,macosx-all
 java/net/MulticastSocket/SetLoopbackMode.java https://github.com/adoptium/infrastructure/issues/699 linux-s390x,aix-all
 java/net/MulticastSocket/SetLoopbackModeIPv4.java https://github.ibm.com/runtimes/backlog/issues/707 linux-s390x,macosx-all