kvserver: reset lb splitter on all queue splits

Previously, we'd only reset the load based splitter state when a load
based split occurred. This was reasonable in most cases, as the odds of
wanting to split for another reason in addition to load is rare but was
nevertheless imperfect. As a result, samples could be left around in the
load based splitter that didn't conform to the range boundaries
post-split.

Informs: #144407
Release note: None

Author: kvoli

pkg/kv/kvserver/split_queue.go

@@ -303,6 +303,9 @@ func (sq *splitQueue) processAttempt(
 			return false, errors.Wrapf(err, "unable to split %s at key %q", r, splitKey)
 		}
 		sq.metrics.SpanConfigBasedSplitCount.Inc(1)
+
+		// Reset the splitter now that the bounds of the range changed.
+		r.loadBasedSplitter.Reset(sq.store.Clock().PhysicalTime())
 		return true, nil
 	}
 
@@ -328,6 +331,9 @@ func (sq *splitQueue) processAttempt(
 			return false, err
 		}
 		sq.metrics.SizeBasedSplitCount.Inc(1)
+
+		// Reset the splitter now that the bounds of the range changed.
+		r.loadBasedSplitter.Reset(sq.store.Clock().PhysicalTime())
 		return true, nil
 	}