FIX: dollar-sign escaping in preprocessLaTeX code‐block handling (#21796)

Co-authored-by: LinYing <linying@momenta.ai>

web/app/components/base/markdown/markdown-utils.ts

 
   const codeBlockRegex = /```[\s\S]*?```/g
   const codeBlocks = content.match(codeBlockRegex) || []
+  const escapeReplacement = (str: string) => str.replace(/\$/g, '_TMP_REPLACE_DOLLAR_')
   let processedContent = content.replace(codeBlockRegex, 'CODE_BLOCK_PLACEHOLDER')
 
   processedContent = flow([
   ])(processedContent)
 
   codeBlocks.forEach((block) => {
-    processedContent = processedContent.replace('CODE_BLOCK_PLACEHOLDER', block)
+    processedContent = processedContent.replace('CODE_BLOCK_PLACEHOLDER', escapeReplacement(block))
   })
 
+  processedContent = processedContent.replace(/_TMP_REPLACE_DOLLAR_/g, '$')
+
   return processedContent
 }