refactor(domain-manager): simplify frontend URL configuration (#10194)

Replaced multiple environment variables for frontend URL construction
with a single FRONTEND_URL variable. This change reduces complexity and
improves clarity by consolidating frontend URL handling into one source.
Updated relevant validations and removed unused variables like
FRONT_PROTOCOL and FRONT_PORT.

Fix #10016

packages/twenty-docker/k8s/manifests/deployment-server.yaml

@@ -33,7 +33,7 @@ spec:
           image: twentycrm/twenty:latest
           imagePullPolicy: Always
           env:
-            - name: PORT
+            - name: NODE_PORT
               value: 3000
             - name: SERVER_URL
               value: "https://crm.example.com:443"