fix(base-driver): Exclude proxied headers from the server response (#21120)

packages/base-driver/lib/jsonwp-proxy/proxy.js

@@ -428,18 +428,13 @@ export class JWProxy {
         /** @type {import('@appium/types').HTTPMethod} */ (req.method),
         req.body
       );
-      for (const [name, value] of _.toPairs(response.headers)) {
-        if (!_.isNil(value)) {
-          res.setHeader(name, _.isBoolean(value) ? String(value) : value);
-        }
-      }
       statusCode = response.statusCode;
     } catch (err) {
       [statusCode, resBodyObj] = getResponseForW3CError(
         isErrorType(err, errors.ProxyRequestError) ? err.getActualError() : err
       );
     }
-    res.set('content-type', 'application/json; charset=utf-8');
+    res.setHeader('content-type', 'application/json; charset=utf-8');
     if (!_.isPlainObject(resBodyObj)) {
       const error = new errors.UnknownError(
         `The downstream server response with the status code ${statusCode} is not a valid JSON object: ` +

packages/base-driver/test/unit/jsonwp-proxy/proxy.spec.js

@@ -7,9 +7,6 @@ function buildReqRes(url, method, body) {
   let req = {originalUrl: url, method, body};
   let res = {};
   res.headers = {};
-  res.set = (k, v) => {
-    res[k] = v;
-  };
   res.setHeader = (k, v) => {
     res.headers[k] = v;
   };