Falsy unsaved changes message

**Describe the bug**
The Unsaved changes message appears when you edit and revert the changes.

**To Reproduce**
1. configure the CMS to work with gihub backend
2. start the cms
3. create a new post and save it
4. make a change and revert it
5. The Unsaved Changes doesn't change to Changes Saved

**Expected behavior**
The Unsaved Changes should be replaced with Changes Saved

**Screenshots**

**Applicable Versions:**

- Decap CMS version: 3.3.2
- Git provider: GitHub
- OS: Mac OS Sonoma 14.4
- Browser version Firefox 129

- Node.JS version: 20.12.2

**CMS configuration**
https://github.com/decaporg/decap-cms/blob/main/dev-test/config.yml
with gitthub backend

**Additional context**

It seems like the issue has been introduced by adding a new line in `packages/decap-cms-core/src/backend.ts#entryToRaw` method

```
let content = format.toFile(entry.get('data').toJS(), fieldsOrder, fieldsComments);
if (content.slice(-1) != '\n') {
// add the EOL if it does not exist.
content += '\n';
}
return content;
}
```

in #7039 while solving #1382
The addition of the newline is conflicting with the trimming the end of content in markdown widget at https://github.com/decaporg/decap-cms/blob/main/packages/decap-cms-widget-markdown/src/serializers/index.js#L151
```
/**
* Return markdown with trailing whitespace removed.
*/
return trimEnd(markdown);
```

Start with packages/decap-cms-core/src/backend.ts at entryToRaw and compare its trailing-newline handling with packages/decap-cms-widget-markdown/src/serializers/index.js, where trimEnd is used. Reproduce the GitHub-backend workflow from the issue, then verify that editing and reverting a saved post changes the status to Changes Saved without introducing a false unsaved state.

Written by the indexing model from the issue text.