refactor(curriculum): improve binary search tree

[zairahira]

Checklist:

• [x] I have read and followed the contribution guidelines.
• [x] I have read and followed the how to open a pull request guide.
• [x] My pull request targets the main branch of freeCodeCamp.
• [x] I have tested these changes either locally on my machine, or GitPod.

Closes #52586

[ghost]

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[Sembauke]

Hey @naomi-lgbt, Do you have a moment to review for the Python team?