Disable packet multiplexing design by default

[cheenamalhotra]

Description

Enables below App Context switches by default until packet multiplexing is ready for production use.

Switch.Microsoft.Data.SqlClient.UseCompatibilityProcessSni
Switch.Microsoft.Data.SqlClient.UseCompatibilityAsyncBehaviour

Disabling feature on main branch until a decision is made to fix the feature design and implementation.

[Copilot]

Pull Request Overview

This PR disables the packet multiplexing design by default by enabling two AppContext switches that maintain compatibility with the previous behavior. The change addresses issues with the new packet multiplexing functionality that is not yet ready for production use.

• Enables UseCompatibilityProcessSni and UseCompatibilityAsyncBehaviour switches by default
• Updates logic to default to true when switches are not explicitly set by users
• Updates tests and comments to reflect the new default behavior

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
LocalAppContextSwitches.cs	Changes default values for compatibility switches from false to true when not explicitly set
LocalAppContextSwitchesTest.cs	Updates unit tests to expect true as default values for the compatibility switches
MultiplexerTests.cs	Updates test helper method to return true as default when switch is not set

[ErikEJ]

LGTM

[benrr101]

Looks reasonable to me.

[paulmedynski]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[cheenamalhotra]

Overtaken by #3556

[cheenamalhotra]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 67.34%. Comparing base (1e1c52a) to head (5b75d81).
⚠️ Report is 13 commits behind head on main.

Files with missing lines	Patch %	Lines
...icrosoft/Data/SqlClient/LocalAppContextSwitches.cs	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3537      +/-   ##
==========================================
- Coverage   69.14%   67.34%   -1.80%     
==========================================
  Files         276      274       -2     
  Lines       62414    62478      +64     
==========================================
- Hits        43154    42075    -1079     
- Misses      19260    20403    +1143     

Flag	Coverage Δ
addons	90.82% <ø> (ø)
netcore	72.35% <50.00%> (-0.61%)	⬇️
netfx	66.17% <50.00%> (-2.26%)	⬇️

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