[6.1] Enable vector tests and validate ref assembly for vector APIs

[apoorvdeshmukh]

Description

This PR ports #3559 to release/6.1
Subset of changes were already present in 6.1 branch, so this is a manual port.

Testing

Enabled Vector and JSON tests.

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[Copilot]

Pull Request Overview

This PR ports changes from #3559 to the release/6.1 branch, enabling Vector and JSON tests for Azure SQL Server. The changes update test conditions to use IsAzureServer instead of specific feature flags and remove the deprecated IsJsonSupported configuration option.

Key changes include:

• Removal of the IsJsonSupported configuration property and its usage
• Updated test conditional attributes from feature-specific checks to Azure server checks
• Code cleanup and organization improvements in Vector API validation tests

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
config.default.json	Removes deprecated IsJsonSupported configuration property
Config.cs	Removes IsJsonSupported field from configuration class
VectorTypeBackwardCompatibilityTests.cs	Updates test conditions from IsVectorSupported to IsAzureServer
VectorAPIValidationTest.cs	Refactors single large test into multiple focused test methods
NativeVectorFloat32Tests.cs	Updates test conditions from IsVectorSupported to IsAzureServer
JsonTest.cs	Updates test conditions from IsJsonSupported to IsAzureServer
JsonStreamTest.cs	Updates test conditions and reduces test data size for performance
JsonBulkCopyTest.cs	Updates test conditions and improves table name generation
DataTestUtility.cs	Removes deprecated vector/JSON support flags and adds IsAzureServer method

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.02%. Comparing base (7a7b54e) to head (fe9f5b7).
⚠️ Report is 9 commits behind head on release/6.1.

Additional details and impacted files

@@               Coverage Diff               @@
##           release/6.1    #3592      +/-   ##
===============================================
- Coverage        69.69%   65.02%   -4.68%     
===============================================
  Files              281      279       -2     
  Lines            62413    61748     -665     
===============================================
- Hits             43500    40151    -3349     
- Misses           18913    21597    +2684     

Flag	Coverage Δ
addons	90.82% <ø> (ø)
netcore	69.30% <ø> (-3.46%)	⬇️
netfx	66.63% <ø> (-2.62%)	⬇️

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