fix: forward proto from reverse proxy

[dhhyi]

PR Type

[x] Bugfix

What Is the Current Behavior?

The protocol used on the topmost reverse proxy is not correctly forwarded to the SSR container.

Steps to reproduce:

1. Install Intershop Helm Charts:

   helm repo add intershop https://intershop.github.io/helm-charts
   helm repo update

2. create minimal values.yaml file for proxying ICM:

   environment:
     - name: PROXY_ICM
       value: "true"
     # needed for SSR as ICM certificate is only valid for *.test.intershop.de
     - name: TRUST_ICM
       value: "true"
   
   # needed for using local images instead of always pulling from docker hub
   # image:
   #   pullPolicy: IfNotPresent
   # cache:
   #   image:
   #     pullPolicy: IfNotPresent

3. Install release:

   helm install dev-release intershop/pwa-main -f values.yaml

4. Forward pwa.example.local to 127.0.0.1 in your hosts file

5. Check the release https://pwa.example.local and observe you are getting mixed content errors

What Is the New Behavior?

The protocol is correctly forwarded to the SSR container using and trusting the X-Forwarded-Proto header.

Does this PR Introduce a Breaking Change?

[ ] Yes
[x] No

Other Information

AB#90392