Move X-Forwarded-Port variable to the location context

Resolves issue #4038 where the X-Forwarded-Port header would be set to the value of the https listening port if all of the following settings were satisfied:
- The ingress controller was started with a non-default HTTPS port set with the `--https-port` argument
- An ingress is created having:
  - the `nginx.ingress.kubernetes.io/auth-url` annotation set
  - TLS enabled

This commit solves this issue by moving the setting of the `pass_server_port` variable from the server, one level down to the location context.

test/e2e-image/Dockerfile

@@ -18,6 +18,7 @@ COPY e2e.sh             /e2e.sh
 COPY cloud-generic      /cloud-generic
 COPY cluster-wide       /cluster-wide
 COPY overlay            /overlay
+COPY namespace-overlays /namespace-overlays
 RUN sed -E -i 's|^- .*deploy/cloud-generic$|- ../cloud-generic|' /overlay/kustomization.yaml
 COPY wait-for-nginx.sh  /
 COPY e2e.test           /