[BUG] Extra escaping character '\' in code samples

## 🐞Describe the bug

When the output is a code sample, we notice an extra escaping character "\\" before $. It makes it impossible to use the code copied from there without removing all the extra characters.

## 🔄 To Reproduce

Ask for code examples, e.g. PHP code.

## 📷 Screenshots

This is a sample of what we get with PHP code. Note the extra "\\" character before variable names:

Start by reproducing the issue with a PHP code-example request and compare the displayed sample with the copied code. Trace the code-sample rendering and escaping path; done means generated examples no longer contain extra backslashes before PHP variable names.

Written by the indexing model from the issue text.