issue: #35846
querycoord will notify proxy to update shard leader cache after
delegator location changes, but during querynode's failure recovery,
some delegator may become unserviceable due to lacking of segments, and
back to serviceable after segment loaded, so we also need to notify
proxy to invalidate shard leader cache when delegator serviceable state
changes.
This PR will maintain querynode's serviceable state during heartbeat,
and notify proxy to invalidate shard leader cache if serviceable state
changes.
Signed-off-by: Wei Liu <wei.liu@zilliz.com>
c84ea5465c