[Tutorials] Consistently use LaTeX delimiter for Docusaurus

This is a duplicate of the same code change in botorch: pytorch/botorch#2752

Docusaurus 3 requires math to be wrapped in $ delimiters. We were trying to be backwards compatible with our existing tutorials by wrapping math blocks in $ delimiters while converting to MDX but properly handling every type of math block (which this was failing to do) is beyond the scope of this script.

Since  these tutorials are intended to be consumed by Docusaurus lets just enforce the $ delimiters when writing tutorials.

scripts/convert_ipynb_to_mdx.py

@@ -324,9 +324,6 @@ def sanitize_mdx(mdx: str) -> str:
 
     # -- KaTeX --
     # Wrap '\begin{}...\end{}' in $$ for KaTeX to work.
-    mdx = re.sub(
-        "(\\\\begin\\\\{(\\w*?)\\\\}(.|\n)*?end\\\\{\\2\\\\})", "$$\\g<1>$$", mdx
-    )
     # Make sure $$ symbols are not escaped and include line breaks.
     mdx = re.sub(
         "\\\\?\\$\\\\?\\$((?:.|\n)*?)\\\\?\\$\\\\?\\$", "\n$$\n\\g<1>\n$$\n", mdx