SearchV2: add more tracing spans (#55488)

* add additional spans to searchv2

* add initial setup span

* add dashboardCount attribute to readDashboard span

* add dashboard count to init org index span

* fix merge

Co-authored-by: Todd Treece <todd.treece@grafana.com>

pkg/services/searchV2/service.go

@@ -81,7 +81,7 @@ func ProvideService(cfg *setting.Cfg, sql *sqlstore.SQLStore, entityEventStore s
 			ac:  ac,
 		},
 		dashboardIndex: newSearchIndex(
-			newSQLDashboardLoader(sql, cfg.Search),
+			newSQLDashboardLoader(sql, tracer, cfg.Search),
 			entityEventStore,
 			extender.GetDocumentExtender(),
 			newFolderIDLookup(sql),