[#764] metrics: Fix epoch metric

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

cmd/frostfs-node/config.go

@@ -562,10 +562,11 @@ func initCfg(appCfg *config.Config) *cfg {
 	relayOnly := nodeconfig.Relay(appCfg)
 
 	netState := newNetworkState()
-	netState.metrics = c.metricsCollector
 
 	c.shared = initShared(appCfg, key, netState, relayOnly)
 
+	netState.metrics = c.metricsCollector
+
 	logPrm, err := c.loggerPrm()
 	fatalOnErr(err)
 	logPrm.SamplingHook = c.metricsCollector.LogMetrics().GetSamplingHook()