platform/service: fix a flaky test (#21497)

app/platform/service.go

@@ -173,7 +173,7 @@ func New(sc ServiceConfig, options ...Option) (*PlatformService, error) {
 	ps.initEnterprise()
 
 	// Step 5: Init Metrics
-	if metricsInterfaceFn != nil {
+	if metricsInterfaceFn != nil && ps.metricsIFace == nil { // if the metrics interface is set by options, do not override it
 		ps.metricsIFace = metricsInterfaceFn(ps, *ps.configStore.Get().SqlSettings.DriverName, *ps.configStore.Get().SqlSettings.DataSource)
 	}