Memory Management: Dispose IDisposable resources correctly in four internal classes

[AndyButland]

Description

Housekeeping PR that ensures four internal IDisposable resources are disposed correctly, in line with .NET best practices.

None of these are suspected to cause real-world problems. The disposed objects are either short-lived, cleaned up at shutdown, or finalized by the GC eventually. However, they are violations of the IDisposable contract and worth fixing for code hygiene.

Testing

Visual inspection will suffice here.

[Copilot]

Pull request overview

Housekeeping changes to tighten IDisposable ownership/cleanup in internal infrastructure and dev-mode components, aligning resource lifetimes with .NET disposal best practices.

Changes:

• Dispose CancellationTokenSource in DatabaseServerMessenger’s dispose path.
• Dispose JsonDocument after deserializing cache refresh instructions in CacheInstructionService.
• Ensure cryptography primitives (ICryptoTransform, CryptoStream) are disposed in legacy password decryption.
• Make InMemoryAssemblyLoadContextManager disposable to unsubscribe from AssemblyLoadContext.Default.Resolving.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/Umbraco.Infrastructure/Sync/DatabaseServerMessenger.cs	Disposes the internal CancellationTokenSource during managed disposal.
src/Umbraco.Infrastructure/Services/CacheInstructionService.cs	Adds disposal of JsonDocument after instruction extraction.
src/Umbraco.Infrastructure/Security/MemberPasswordHasher.cs	Scopes crypto resources with using to ensure deterministic cleanup.
src/Umbraco.Cms.DevelopmentMode.Backoffice/InMemoryAuto/InMemoryAssemblyLoadContextManager.cs	Implements IDisposable to unsubscribe the default ALC resolving handler.

[Migaroez]

LGTM