style: enable WhitespaceAround in checktyle

[vil02]

Related to #5119.

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• 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 ✅

Project coverage is 39.82%. Comparing base (7b17ead) to head (c1832e4).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #5241   +/-   ##
=========================================
  Coverage     39.82%   39.82%           
- Complexity     2436     2437    +1     
=========================================
  Files           517      517           
  Lines         15476    15476           
  Branches       2958     2958           
=========================================
+ Hits           6163     6164    +1     
  Misses         9022     9022           
+ Partials        291      290    -1     

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