Set log level of PHC dropping an endpoint to debug (zalando#3098)

This is needed not to log too many lines. Moreover, the information
about requests amount could be seen in the metrics, the information
about IPs being mitigated could be get from updateStats logs

Signed-off-by: Roman Zavodskikh <roman.zavodskikh@zalando.de>
Co-authored-by: Roman Zavodskikh <roman.zavodskikh@zalando.de>

proxy/healthy_endpoints.go

@@ -26,7 +26,7 @@ func (h *healthyEndpoints) filterHealthyEndpoints(ctx *context, endpoints []rout
 	for _, e := range endpoints {
 		dropProbability := e.Metrics.HealthCheckDropProbability()
 		if p < dropProbability {
-			ctx.Logger().Infof("Dropping endpoint %q due to passive health check: p=%0.2f, dropProbability=%0.2f",
+			ctx.Logger().Debugf("Dropping endpoint %q due to passive health check: p=%0.2f, dropProbability=%0.2f",
 				e.Host, p, dropProbability)
 			metrics.IncCounter("passive-health-check.endpoints.dropped")
 			unhealthyEndpointsCount++