ZTS: Apply zfs_bclone_enabled to bclone tests

If block cloning is disabled by default then enable it when running
the bclone tests.  Follow up to openzfs#15529.

Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes openzfs#15796

tests/zfs-tests/tests/functional/bclone/cleanup.ksh

@@ -34,4 +34,11 @@
 
 log_must zfs destroy $TESTSRCFS
 log_must zfs destroy $TESTDSTFS
-default_cleanup
+
+default_cleanup_noexit
+
+if tunable_exists BCLONE_ENABLED ; then
+	log_must restore_tunable BCLONE_ENABLED
+fi
+
+log_pass

tests/zfs-tests/tests/functional/bclone/setup.ksh

@@ -36,6 +36,11 @@ if ! command -v clonefile > /dev/null ; then
 	log_unsupported "clonefile program required to test block cloning"
 fi
 
+if tunable_exists BCLONE_ENABLED ; then
+	log_must save_tunable BCLONE_ENABLED
+	log_must set_tunable32 BCLONE_ENABLED 1
+fi
+
 DISK=${DISKS%% *}
 
 default_setup_noexit $DISK "true"