AI Blurp

This pull request includes several improvements and refactorings to theSplitPacketTest class and theDataTestUtility class in the Microsoft.Data.SqlClient test suite. The most important changes include adding new utility methods, refactoring existing methods, and enhancing the test class with proper resource disposal.

Improvements and refactorings:

• src/Microsoft.Data.SqlClient/tests/ManualTests/DataCommon/DataTestUtility.cs: Added new methodsIsNotNamedInstance andIsLocalHost to theDataTestUtility class for better connection string handling and test conditions.

Enhancements to test class:

• src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/SplitPacketTest/SplitPacketTest.cs: Refactored theSplitPacketTest class to use private fields with underscores, addedCancellationToken support to theSetupProxy method, and implemented theIDisposable interface for proper resource cleanup.[1][2][3][4][5]

These changes enhance the code readability, maintainability, and ensure that resources are properly managed during the tests.

Human stuff

This removes the ActiveIssue 5538 from the SplitPacketTest
It makes sure that the test is only run on localhost and without named instances due to the fact that the tests are proxying the requests.

Also added IDisposable cleanup so that the started threads don't hang around.