style: enable FinalClass in checkstyle

[CodaBlurd]

Related to #5119.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 20.00000% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 38.25%. Comparing base (52f15b2) to head (fe9e3e8).

Files	Patch %	Lines
...thms/datastructures/dynamicarray/DynamicArray.java	0.00%	1 Missing ⚠️
...datastructures/lists/Merge_K_SortedLinkedlist.java	0.00%	1 Missing ⚠️
...healgorithms/datastructures/trees/GenericTree.java	0.00%	1 Missing ⚠️
...lgorithms/datastructures/trees/TreeRandomNode.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5154      +/-   ##
============================================
- Coverage     38.26%   38.25%   -0.01%     
+ Complexity     2362     2361       -1     
============================================
  Files           516      516              
  Lines         15310    15310              
  Branches       2958     2958              
============================================
- Hits           5858     5857       -1     
  Misses         9165     9165              
- Partials        287      288       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.