gh-139736: Fix argparse indentation overshoot

[9001]

When calculating the --help indentation, strip colors before counting the action length.

• Issue: argparse indentation overshoots due to colors #139736

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[9001]

The argparse tests failed because the previous indentation amount is expected; should I go over the tests and adjust them accordingly?

[savannahostrowski]

@9001 Thanks for catching this. I was able to reproduce this, and it appears that those tests were introduced in #133941, following the change in spacing with #130645. So yeah, I think we can update the tests to reflect the correct spacing.

[9001]

Alright -- I believe the remaining test failure is unrelated. Please let me know if there is anything more to be done at this point :)

[hugovk]

I restarted the failure and it passed 👍

[savannahostrowski]

LGTM! Thanks so much!

[miss-islington-app]

Thanks @9001 for the PR, and @savannahostrowski for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

[bedevere-app]

GH-139793 is a backport of this pull request to the 3.14 branch.