[Markdown] Do not auto close angle brackets inside latex blocks

Does this issue occur when all extensions are disabled?: No

This issue is part of the bundled markdown-basics extension.

• VS Code Version: 1.105.0
• OS Version: Windows 11 24H2 26100.6899

Steps to Reproduce:

1. Open an arbitary markdown file
2. Type a < inside $ ... $ or $$ ... $$
3. A > will be added as part of the auto-closing
4. However, HTML tags are not allowed inside latex blocks, and when people use latex blocks, mostly they will use < as less than meaning instead of left angle bracket, so it should not be auto-closed