The lctl set_param -P functionality was landed via
LU-3155 for 2.5.0 and deprecates lctl conf_param usage. There is a deprecation message printed in jt_lcfg_mgsparam() since 2.7.53 that conf_param is obsolete and set_param should be used instead.
The test scripts need to be changed over to use "lctl set_param -P" exclusively, both to quiet the deprecation warning, as well as verify that the "lctl set_param -P" functionality is working correctly.
For now, I'm going to bump the deprecation warning to 2.8.53 to give us time to make this change in the 2.9 release cycle since there isn't enough time to do it for 2.8.0 anymore.