Reduce complexity linear_discriminant_analysis. (#2452)

* Reduce complexity linear_discriminant_analysis.

* Fix whitespace

* Update machine_learning/linear_discriminant_analysis.py

Co-authored-by: Dhruv Manilawala <dhruvmanila@gmail.com>

* fixup! Format Python code with psf/black push

* Fix format to surpass pre-commit tests

* updating DIRECTORY.md

* Update machine_learning/linear_discriminant_analysis.py

Co-authored-by: Dhruv Manilawala <dhruvmanila@gmail.com>

* fixup! Format Python code with psf/black push

Co-authored-by: Dhruv Manilawala <dhruvmanila@gmail.com>
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>