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/namespace-overlays/forwarded-port-headers/kustomization.yaml

@@ -0,0 +1,16 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+patchesJson6902:
+  - target:
+      group: apps
+      version: v1
+      kind: Deployment
+      name: nginx-ingress-controller
+    path: deployment-patch.yaml
+  - target:
+      version: v1
+      kind: Service
+      name: ingress-nginx
+    path: service-patch.yaml
+bases:
+- ../../overlay