JGroups discovery protocol was one of the things that changed quite a bit in the new distribution. See the new guide here: Keycloak - Server - Configuring distributed caches
If you end up needing to write your own Infinispan config file, there a discussion here about it. Even though JDBC_PING is discussed, you can use the same method for any custom configuration: Use of JDBC_PING with Keycloak 17 (Quarkus distro)