Also percona-xtradb-cluster-galera-2.x should be removed, as it was used by percona-xtradb-cluster-5.5 and nothing else, and percona-xtradb-cluster-5.6 uses percona-galera-3 instead.
Also percona- xtradb- cluster- galera- 2.x should be removed, as it was used by percona- xtradb- cluster- 5.5 and nothing else, and percona- xtradb- cluster- 5.6 uses percona-galera-3 instead.