runtime/metrics: don't collect on startup or shutdown

Metrics providers don't like when metrics are pushed on irregular
intervals and reject these metrics, causing unnecessary error logs.

runtimes/go/appruntime/infrasdk/metrics/metrics.go

@@ -59,7 +59,6 @@ func (mgr *Manager) Shutdown(p *shutdown.Process) error {
 	<-p.ServicesShutdownCompleted.Done()
 	<-p.OutstandingTasks.Done()
 
-	mgr.collectNow(p.ForceShutdown)
 	mgr.cancel()
 
 	if mgr.exp != nil {
@@ -76,10 +75,6 @@ func (mgr *Manager) BeginCollection() {
 		return
 	}
 
-	ctx, cancel := context.WithTimeout(context.Background(), 25*time.Second)
-	mgr.collectNow(ctx)
-	cancel()
-
 	interval := mgr.runtime.Metrics.CollectionInterval
 	if interval <= 0 {
 		interval = time.Minute