lib/storage: fix metric vm_object_references{type="indexdb"} (#6937)

follow up
4ecc370acb

### Describe Your Changes

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specific as possible to help others understand the purpose and impact of
your modifications.

### Checklist

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- [ ] My change adheres [VictoriaMetrics contributing
guidelines](https://docs.victoriametrics.com/contributing/).

docs/changelog/CHANGELOG.md

@@ -25,6 +25,7 @@ See also [LTS releases](https://docs.victoriametrics.com/lts-releases/).
 
 * BUGFIX: [vmagent dashboard](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/dashboards/vmagent.json): fix legend captions for stream aggregation related panels. Before they were displaying wrong label names.
 * BUGFIX: [vmgateway](https://docs.victoriametrics.com/vmgateway/): add missing `datadog`, `newrelic`, `opentelemetry` and `pushgateway` routes to the `JWT` authorization routes. Allows prefixed (`promtheus/graphite`) routes for query requests.
+* BUGFIX: [Single-node VictoriaMetrics](https://docs.victoriametrics.com/) and `vmstorage` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/cluster-victoriametrics/): fix metric `vm_object_references{type="indexdb"}`. Previously, it was overcounted.
 
 ## [v1.103.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.103.0)
 

lib/storage/index_db.go

@@ -224,6 +224,9 @@ func (db *indexDB) UpdateMetrics(m *IndexDBMetrics) {
 	m.TagFiltersToMetricIDsCacheMisses += cs.Misses
 
 	m.IndexDBRefCount += uint64(db.refCount.Load())
+
+	// this shouldn't increase the MissingTSIDsForMetricID value,
+	// as we only count it as missingTSIDs if it can't be found in both the current and previous indexdb.
 	m.MissingTSIDsForMetricID += db.missingTSIDsForMetricID.Load()
 
 	m.DateRangeSearchCalls += db.dateRangeSearchCalls.Load()
@@ -252,7 +255,6 @@ func (db *indexDB) UpdateMetrics(m *IndexDBMetrics) {
 		m.GlobalSearchCalls += extDB.globalSearchCalls.Load()
 
 		m.MissingMetricNamesForMetricID += extDB.missingMetricNamesForMetricID.Load()
-		m.IndexDBRefCount += uint64(extDB.refCount.Load())
 	})
 }