fix: update next-issue recommendation bot comment logic

[parvninama]

Changes

• Introduced explicit tracking variables in the recommendation logic
• Derived completedLabel dynamically based on the linked issue’s difficulty
• Improved recommendation selection behavior
• Prevented self-recommendation by filtering out the issue that was just completed from the recommendation list

Dry runs

• In Progress

Fixes #1593

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@           Coverage Diff           @@
##             main    #1617   +/-   ##
=======================================
  Coverage   92.89%   92.89%           
=======================================
  Files         140      140           
  Lines        8765     8765           
=======================================
  Hits         8142     8142           
  Misses        623      623           

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