gh-126882: Fix indentation in code sample block.

[javert42]

Both code blocks are text from a Python REPL session. pycon is an alias for the Python REPL language used for syntax highlighting. The problem is that the lines all begin with unnecessary spaces, while pycon expects each line of input to begin with '^>>>' or '^...' (see link below).

Changing the language type to python would also work, but pycon seems to be appropriate for this case (after getting rid of the leading spaces).

This change keeps the language type (pycon) and removes the leading spaces.

Notes:
I believe this is what is being used for syntax highlighting in both GitHub and VS Code:
https://github.com/highlightjs/highlight.js/blob/c49081a84fc5de213383287b68ce2ecc238e537d/src/languages/python-repl.js

• Issue: Internal docs: Update code blocks in garbage_collector.md to improve syntax highlighting #126882

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[tomasr8]

Thanks! There's a couple more code blocks in the file that should be fixed as well

[javert42]

I changed the language type from pycon to python and got rid of the leading spaces in all of the code blocks in this document.

One of the code blocks that I missed in my first commit has line-comments inserted between lines of the REPL session. Using pycon wouldn't highlight these comments because their lines don't start with >>>. Adding the >>> in front of every comment would correct the syntax, and enable comment highlighting, but it gets a bit messy. Just changing the language type to python provides the expected syntax-highlighting, and allows the author a little license to stray from strict representation of an actual REPL session.