* DAOS-11955 pool: Ensure a PS is inside its pool

It was found that a PS leader may enter ds_pool_plan_svc_reconfs with
itself being an undesirable replica. This may lead to an assertion
failure at "move n replicas from undesired to to_remove" in
ds_pool_plan_svc_reconfs. Moreover, such a PS leader may be outside of
the pool group, making it incapable of performing many duties that
involve collective communication.

This patch therefore ensures that a PS leader will remove undesirable PS
replicas synchronously before committing a pool map modification that
introduces new undesirable PS replicas. (If we were to keep an
undesirable PS replica, it might become a PS leader.)

  - Extend and clean up pool_svc_sched.
      * Allow pool_svc_reconf_ult to return an error, so that we can
	fail a pool map modification if its synchronous PS replica
        removal fails.
      * Allow pool_svc_reconf_ult to get an argument, so that we can
	tell pool_svc_reconf_ult whether we want a synchronous
        remove-only run or an asyncrhonous add-remove run.
      * Move pool_svc_sched.{psc_svc_rf,psc_force_notify} up to
	pool_svc.
  - Prevent pool_svc_step_up_cb from canceling in-progress
    reconfigurations by comparing pool map versions for which the
    reconfigurations are scheduled.
  - Rename POOL_GROUP_MAP_STATUS to POOL_GROUP_MAP_STATES so that we are
    consistent with the pool_map module.

Signed-off-by: Li Wei <[email protected]>
Signed-off-by: Jeff Olivier <[email protected]>

This patch cleans up the pool map update logging on the client side and
the engine side. A few notable changes:

  - In dc_pool_map_update, if the incoming map is of the same version as
    the one we already have, do not perform the update.

Signed-off-by: Li Wei <[email protected]>