Revert "b/360833010 disable punch and stat collectives (#14974)" (#15700)

This reverts commit a2819ec.

Author: jolivier23

src/object/cli_mod.c

@@ -186,7 +186,7 @@ dc_obj_init(void)
 	if (rc != 0)
 		goto out_class;
 
-	obj_coll_thd = 0; /* Was OBJ_COLL_THD_MIN, restore when leak is fixed */
+	obj_coll_thd = OBJ_COLL_THD_MIN;
 	d_getenv_uint("DAOS_OBJ_COLL_THD", &obj_coll_thd);
 	if (obj_coll_thd == 0) {
 		D_INFO("Disable collective operation.\n");