fix x-forwarded-port header (#63303)

Follow up to #61133 that will
rely on `x-forwarded-proto` value if it exists in order to default the
`x-forwarded-port` value.

Closes NEXT-2820

packages/next/src/server/base-server.ts

@@ -889,7 +889,11 @@ export default abstract class Server<ServerOptions extends Options = Options> {
       }
 
       const { originalRequest } = req as NodeNextRequest
-      const isHttps = !!(originalRequest?.socket as TLSSocket)?.encrypted
+      const xForwardedProto = originalRequest?.headers['x-forwarded-proto']
+      const isHttps = xForwardedProto
+        ? xForwardedProto === 'https'
+        : !!(originalRequest?.socket as TLSSocket)?.encrypted
+
       req.headers['x-forwarded-host'] ??= req.headers['host'] ?? this.hostname
       req.headers['x-forwarded-port'] ??= this.port
         ? this.port.toString()