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 79.85%. Comparing base (631eae3) to head (3e0d6b9).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7486      +/-   ##
============================================
- Coverage     79.86%   79.85%   -0.02%     
+ Complexity     7333     7321      -12     
============================================
  Files           808      807       -1     
  Lines         23833    23813      -20     
  Branches       4690     4686       -4     
============================================
- Hits          19035    19016      -19     
  Misses         4036     4036              
+ Partials        762      761       -1     

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