### Describe the issue

I set `axios.defaults.headers.common['Content-Type'] = 'application/json'`. When firing a `axios.patch` request (without a config), the request uses `application/x-www-form-urlencoded` instead.

### Example Code

```js
// This does not work as expected:
axios.defaults.headers.common['Content-Type'] = 'application/json'

// This does:
axios.defaults.headers.common['Content-Type'] = 'application/json'
axios.defaults.headers.patch['Content-Type'] = 'application/json'
```


### Expected behavior

I expected POST requests to use `axios.defaults.headers.common`, too.

I think this is where the problem (or intended behaviour) comes from: https://github.com/axios/axios/blob/3f53eb6960f05a1f88409c4b731a40de595cb825/lib/core/dispatchRequest.js#L46

### Axios Version

1.4.0

### Adapter Version

_No response_

### Browser

Firefox

### Browser Version

116.0.3 (64-bit)

### Node.js Version

_No response_

### OS

_No response_

### Additional Library Versions

_No response_

### Additional context/Screenshots

_No response_
lib/defaults/index.js
'use strict';
import utils from '../utils.js';
import AxiosError from '../core/AxiosError.js';
import transitionalDefaults from './transitional.js';
import toFormData from '../helpers/toFormData.js';
import toURLEncodedForm from '../helpers/toURLEncodedForm.js';
import platform from '../platform/index.js';
import formDataToJSON from '../helpers/formDataToJSON.js';
const DEFAULT_CONTENT_TYPE = {
  'Content-Type': undefined
};
/**
 * It takes a string, tries to parse it, and if it fails, it returns the stringified version
 * of the input
 *
 * @param {any} rawValue - The value to be stringified.
 * @param {Function} parser - A function that parses a string into a JavaScript object.
 * @param {Function} encoder - A function that takes a value and returns a string.
 *
 * @returns {string} A stringified version of the rawValue.
 */
function stringifySafely(rawValue, parser, encoder) {