Importing from Postman sligthly fails with application/x-www-form-urlencoded POST

### Expected Behavior

The import from Postman should create a list of API calls, that could be immediately called.

### Actual Behavior

The given call is imported but it fail in an unexpected way.

### Reproduction Steps

Given a **Postman** export file with at least an api call with a `POST` using `application/x-www-form-urlencoded`:
* import from file
* perform import (this shoul work smootly)
* try to call POST application/x-www-form-urlencoded api

### Is there an existing issue for this?

- [X] I have searched the [issue tracker](https://www.github.com/Kong/insomnia/issues) for this problem.

### Additional Information

## Workaround

If you go in the Form menu and you pick again `Form URL encoded`, which may be already selected from the import, everything should go back to a regular api call.

### Insomnia Version

2021.7.2

### What operating system are you using?

macOS

### Operating System Version

Mac OS Mojave

### Installation method

homebrew

### Last Known Working Insomnia version

_No response_