Remove markdown backend limit of 50 nodes for wiki and repository files

What does this MR do and why?

In Uplift limit on Math diagrams on wiki pages (!88375 - merged), limits on rendering math in wiki pages and repository files was removed since those have higher privileges and are more trusted.

There was still a limit imposed by the backend code of 50 nodes. This MR removes that limit for wiki pages and repository files to line up with how the other limits are handled.

How to set up and validate locally

1. Add new page to the wiki in a project and add the following markdown:

   $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$
   $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$
   $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$
   $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$
   $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$ + $`a^2+b^2=c^2`$

2. When viewing that page, you should see all the math rendered completely.

3. Create or edit a repository file (such as the README.md), and add the above markdown. Viewing that file you should see all the math rendered.

4. Go to an issue and add the above markdown either to the description or a comment. The the first 50 math nodes will be rendered, and the rest will appear as inline code.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #368009 (closed)