Fix code blocks indentation

Why is this change being made?

The current Release Post MR template has incorrectly nested code blocks in Markdown, which leads to parts of the description being incorrectly included in the code block, and some code blocks are incorrectly lined up with their list items:

This MR correctly indents all code blocks.

I also fixed this in the current MR: !117273 (merged).

Author Checklist

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