refactor: unify Dijkstra on efficient PriorityQueue implementation

[priyanshuvishwakarma273403]

Description

This PR unifies the Dijkstra implementation under datastructures/graphs/ to use a single, efficient, priority-queue-based (using Java's PriorityQueue with lazy updates) implementation. It removes the redundant DijkstraOptimizedAlgorithm class.

Related Issue

Fixes #7458

Changes Made

• Updated DijkstraAlgorithm.java to use a PriorityQueue with $O((V + E) \log V)$ time complexity, utilizing a static inner Node helper class.
• Removed the redundant DijkstraOptimizedAlgorithm.java and DijkstraOptimizedAlgorithmTest.java.
• Verified that all robust test cases in DijkstraAlgorithmTest.java run and pass successfully.

Checklist

• Code compiles successfully.
• Redundant implementations removed.
• Unit tests passed.
• Followed repository code style rules.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.88%. Comparing base (0fe06ac) to head (25746ed).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7486      +/-   ##
============================================
- Coverage     79.88%   79.88%   -0.01%     
+ Complexity     7344     7332      -12     
============================================
  Files           809      808       -1     
  Lines         23851    23831      -20     
  Branches       4697     4693       -4     
============================================
- Hits          19054    19037      -17     
+ Misses         4036     4035       -1     
+ Partials        761      759       -2     

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