ZTS: Add zfs_clone_livelist_dedup.ksh to Makefile.am

Commit 86b5f4c12 added a new zfs_clone_livelist_dedup.ksh test case
but didn't include it in the Makefile.am. This results in the test
not being included in the dist tarball so it's never run by the CI.

Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes: #12224