DashboardStore: Use ReplDB and get dashboard quotas from the ReadReplica (#90235)

* Use ReplDB in dashboard store and update all fixtures - no other changes

* just moving dashboard counts for now

* find the missing test fixture

pkg/infra/db/dbrepl.go

@@ -1,9 +1,14 @@
 package db
 
-import "github.com/grafana/grafana/pkg/services/sqlstore"
+import (
+	"github.com/grafana/grafana/pkg/services/sqlstore"
+)
 
 type ReplDB interface {
 	// DB is the primary database connection.
 	DB() *sqlstore.SQLStore
+
+	// ReadReplica is the read-only database connection. If no read replica is configured, the implementation must return the primary DB.
+	// TODO: ReadReplica will take a list of replicas and load-balance across them in a future milestone.
 	ReadReplica() *sqlstore.SQLStore
 }