Issue #5443 - Forwarding Headers are optional

The `X-Proxied-Https: off` case should have an implied port
not a hardcoded port.

Signed-off-by: Joakim Erdfelt <joakim.erdfelt@gmail.com>

jetty-server/src/main/java/org/eclipse/jetty/server/ForwardedRequestCustomizer.java

@@ -880,7 +880,7 @@ public class ForwardedRequestCustomizer implements Customizer
             {
                 _secure = false;
                 updateProto(HttpScheme.HTTP.asString(), Source.XPROXIED_HTTPS);
-                updatePort(80, Source.XPROXIED_HTTPS);
+                updatePort(MutableHostPort.IMPLIED, Source.XPROXIED_HTTPS);
             }
             else
             {