[BUG] In the Submit an app UI, when working on a Session Auth based app, the request content-type application/x-www-form-urlencoded is broken

**Describe the bug**
When you try to submit an app with the Submit an app UI, and the app being Session Auth, if you specify `application/x-www-form-urlencoded` as the content-type, it is ignored no matter how you try to override it.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to 'Submit an app UI
2. Enter required meta data in "basic info" tab.
3. Enter custom field required by the app's Session Auth. Eg. client_id and client_secret for an app using the client_credentials grant.
4. Setup the access token request, specify `application/x-www-form-urlencoded` under headers tab or select `application/x-www-form-urlencoded` in the body tab .
5. Hit "Test up until accessToken request"
6. Notice ow the accessToken request is not executed, and no response is shown

**Expected behavior**
The accessToken request should have executed, with an accompanying response.

**Screenshots**
Eg. of accessToken request execution for Kiwify app:

**Desktop (please complete the following information):**
- OS: Windows 11
- Browser Firefox
- Version 127.0.2

**Additional context**
Occured recently when trying to submit [Kiwify ](https://pipedream.com/submit-an-app/kiwify?tab=basic-info)app