[manual] Merge release/9.0-staging into release/9.0

[jozkee]

MERGE COMMIT!!!!!

[Copilot]

Pull Request Overview

This merge brings the release/9.0-staging branch into release/9.0 and incorporates certificate caching functionality, dependency updates, and infrastructure improvements.

• Introduces certificate caching logic and cleanup timer mechanisms in WinHttpHandler and related callbacks.
• Updates dependency versions across project files and improves CI pipeline configurations.
• Makes minor changes in coreclr components (threads, profiling, GC) and ref assemblies.

Reviewed Changes

Copilot reviewed 47 out of 47 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/libraries/System.Net.Http.WinHttpHandler/src/System/Net/Http/WinHttpRequestCallback.cs	Adds callback logic for handling server connection events and certificate caching removal.
src/libraries/System.Net.Http.WinHttpHandler/src/System/Net/Http/WinHttpHandler.cs	Implements certificate cache management with timer cleanup and updates status callback flags.
src/libraries/System.Net.Http.WinHttpHandler/src/System/Net/Http/CachedCertificateValue.cs	Introduces new types for cached certificate storage and defines equality semantics for cache keys.
src/libraries/System.Net.Http.WinHttpHandler/src/System.Net.Http.WinHttpHandler.csproj	Includes new source file and package reference updates.
src/libraries/System.DirectoryServices.Protocols/ref/System.DirectoryServices.Protocols.cs	Wraps properties with conditional compilation for NET.
src/libraries/Common/tests/TestUtilities/System/PlatformDetection.Unix.cs	Updates OpenSSL version detection logic.
src/libraries/Common/src/Interop/Windows/WinHttp/Interop.winhttp_types.cs	Defines WINHTTP_CONNECTION_INFO to avoid alignment issues.
src/installer/pkg/sfx/installers/dotnet-runtime-deps/dotnet-runtime-deps-debian.proj	Updates KnownLibIcuVersion to include newer ICU versions.
src/coreclr/vm/threads.cpp	Adds handling for TS_DebugWillSync during thread termination.
src/coreclr/jit/fgprofilesynthesis.cpp	Improves safety against division by zero using a max guard.
src/coreclr/gc/gcpriv.h	Updates free region constants and introduces new GC helper methods.
Various pipeline and version files	Updates dependency versions and Docker image references to newer releases.

Comments suppressed due to low confidence (1)

src/libraries/System.Net.Http.WinHttpHandler/src/System/Net/Http/CachedCertificateValue.cs:38

• The override of Equals(object) in CachedCertificateKey currently throws an exception. Consider implementing a proper equality comparison to support boxed comparisons without runtime exceptions.

public override bool Equals(object? obj) { throw new Exception("Unreachable"); }

[jozkee]

/ba-g #115628.