kvserver: remove duplicate logging in s-rebalancer

Previously, the store rebalancer would log `load-based replica transfers
successfully brought...` even when the store was not below the max
threshold. The store rebalancer also logs when there are no available
replica rebalancing actions remaining but the store still above the
desired load threshold: `ran out of replicas worth transferring and
load`. This log line was duplicated in both the post range rebalancing
phase and in exiting the range rebalancing phase.

This commit stops duplication by removing the exit log line and ensures
that the `load-based replica transfers successfully brought...` log line
occurs only when actually successful.

Resolves: #98867

Release note: None

pkg/kv/kvserver/store_rebalancer.go

@@ -592,6 +592,7 @@ func (sr *StoreRebalancer) LogRangeRebalanceOutcome(ctx context.Context, rctx *R
 			"ran out of replicas worth transferring and load %s is still above desired threshold %s; will check again soon",
 			rctx.LocalDesc.Capacity.Load(), rctx.maxThresholds)
 		sr.metrics.ImbalancedStateOverfullOptionsExhausted.Inc(1)
+		return
 	}
 
 	// We successfully rebalanced below or equal to the max threshold,
@@ -623,9 +624,6 @@ func (sr *StoreRebalancer) RebalanceRanges(
 	)
 
 	if candidateReplica == nil {
-		log.KvDistribution.Infof(ctx,
-			"ran out of replicas worth transferring and load %s is still above desired threshold %s; will check again soon",
-			rctx.LocalDesc.Capacity.Load(), rctx.maxThresholds)
 		return NoRebalanceTarget, candidateReplica, voterTargets, nonVoterTargets
 	}