[#2024] Fix promoted folding range tests

Motivation and Context

Folding range tests were promoted and some TODOs were left. This MR addresses it.

Related issues

Partially resolves #2024.

Checklist for the LIGO Language Server

• I checked whether I need to update the README.md file for the plugin and did so if necessary:
  • If I implemented a new LSP request, I added it to the list of supported features that may be disabled
  • If I implemented a new LSP method, I added it to the list of supported functionality
• I checked that my changes work in Emacs, Vim, and Visual Studio Code
• (Before merging) The commit history is squashed and prettified, and follows the Serokell commit policy, or the MR is set to squash the commits

Description

See the commit message.

Component

• compiler
• website
• webide
• vscode-plugin
• debugger

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Performance improvement (non-breaking change that improves performance)
• None (change with no changelog)

Changelog

Fixed an issue with folding ranges using an incorrect range for JsLIGO variant types with a leading vertical bar.

Checklist:

• Changes follow the existing coding style (use dune @fmt to check).
• Tests for the changes have been added (for bug fixes / feature).
• Documentation has been updated.
• Changelog description has been added (if appropriate).
• Start titles under ## Changelog section with #### (if appropriate).
• There is no image or uploaded file in changelog
• Examples in changed behaviour have been added to the changelog (for breaking change / feature).

changelog/2866

+
+author: heitor.toledo
+description: "\\n\\nFixed an issue with folding ranges using an incorrect range for JsLIGO variant types with a leading vertical bar.\\n\\n"
+merge_request: '2866'
+title: "[#2024] Fix promoted folding range tests"
+type: fixed
+            
\ No newline at end of file