Fix NON_UNIQUE value inconsistency in DatabaseMetaData.getIndexInfo()

[Ananya2]

Problem

DatabaseMetaData.getIndexInfo() was returning incorrect NON_UNIQUE values due to inconsistent handling between sp_statistics and sys.indexes result sets.

• sp_statistics: NON_UNIQUE with 1 = not unique, 0 = unique
• sys.indexes: is_unique with 1 = unique, 0 = not unique

The method was merging results from both sources without properly converting the sys.indexes.is_unique values to the expected JDBC NON_UNIQUE format, causing the same index to appear as both unique and non-unique.

Solution

• Added proper conversion logic: CASE WHEN i.is_unique = 1 THEN 0 ELSE 1 END AS NON_UNIQUE
• Applied consistent NON_UNIQUE value mapping across all index queries
• Ensured compatibility with both regular SQL Server and Azure Synapse Analytics

Testing

• Verified correct NON_UNIQUE values for unique and non-unique indexes

Closes #2771

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 52.32%. Comparing base (02ee86c) to head (29724fb).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #2773   +/-   ##
=========================================
  Coverage     52.32%   52.32%           
- Complexity     4140     4151   +11     
=========================================
  Files           149      149           
  Lines         34241    34241           
  Branches       5718     5718           
=========================================
+ Hits          17915    17916    +1     
- Misses        13830    13838    +8     
+ Partials       2496     2487    -9     

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