refactor: clean long division code

[saahil-mahato]

Description

There was a redundant code block in LongDivision.java. This PR simply deletes it and does a few minor code quality modifications.

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized it.
• [x] All filenames are in PascalCase.
• [x] All functions and variable names follow Java naming conventions.
• [x] All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• [x] All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 64.13%. Comparing base (9b52ac9) to head (4769e6e).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5776      +/-   ##
============================================
- Coverage     64.14%   64.13%   -0.01%     
+ Complexity     4205     4204       -1     
============================================
  Files           587      587              
  Lines         16390    16384       -6     
  Branches       3163     3161       -2     
============================================
- Hits          10513    10508       -5     
  Misses         5448     5448              
+ Partials        429      428       -1     

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