[#424] morph: Fix cache metrics

Use separate morph cache metrics for node and IR

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

pkg/morph/metrics/metrics.go

@@ -15,3 +15,7 @@ func (NoopRegister) IncSwitchCount()                                           {
 func (NoopRegister) SetLastBlock(uint32)                                       {}
 func (NoopRegister) IncNotificationCount(string)                               {}
 func (NoopRegister) ObserveInvoke(string, string, string, bool, time.Duration) {}
+
+type NoopMorphCacheMetrics struct{}
+
+func (m *NoopMorphCacheMetrics) AddMethodDuration(string, bool, time.Duration) {}