Delete random bits of unused Razor code

[davidwengier]

Decided to do a pass now that sonic is merged. Was hoping for more stale completion code to come up, but I'm guessing there are more thread to pull there, and I guess they need to be done slowly.

Microsoft Reviewers: Open in CodeFlow

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[Copilot]

Pull request overview

This PR removes a collection of unused/obsolete Razor product and test code (constants, small helper APIs, and legacy completion/telemetry plumbing) and adjusts remaining call sites accordingly to keep the codebase smaller and easier to maintain.

Changes:

• Deleted unused integration-test helpers and VS-layer helper types/constants.
• Simplified RemoteSnapshotManager (removed telemetry dependency + removed unused APIs) and updated tests/benchmarks to use the new construction pattern.
• Removed unused overloads/helpers across formatting/completion/project-system areas, and inlined the Razor configuration string in test/benchmark globalconfig generation.

Reviewed changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/Razor/src/Razor/test/Microsoft.VisualStudio.Razor.IntegrationTests/WellKnownProjectTemplates.cs	Removed unused template constants helper.
src/Razor/src/Razor/test/Microsoft.VisualStudio.Razor.IntegrationTests/InProcess/WellKnownCommandNames.cs	Removed unused command name constants helper.
src/Razor/src/Razor/test/Microsoft.VisualStudio.Razor.IntegrationTests/InProcess/SolutionExplorerInProcess.cs	Removed unused project-template add helpers and related template-path logic.
src/Razor/src/Razor/test/Microsoft.CodeAnalysis.Remote.Razor.UnitTests/CodeActions/HtmlCodeActionResolverTest.cs	Updated to construct RemoteSnapshotManager without telemetry.
src/Razor/src/Razor/test/Microsoft.CodeAnalysis.Remote.Razor.UnitTests/CodeActions/HtmlCodeActionProviderTest.cs	Updated to construct RemoteSnapshotManager without telemetry.
src/Razor/src/Razor/test/Microsoft.CodeAnalysis.Razor.CohostingShared.UnitTests/RazorDocumentMappingServiceTest.cs	Updated to construct RemoteSnapshotManager without telemetry.
src/Razor/src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common.Tooling/Workspaces/RazorProjectBuilder.cs	Inlined Razor configuration name in globalconfig text and removed unused dependency.
src/Razor/src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common.Tooling/TestProjectData.cs	Removed dependency on deleted project-system types and added minimal local test-only HostProject/HostDocument records.
src/Razor/src/Razor/src/Microsoft.VisualStudio.RazorExtension/SyntaxVisualizer/SyntaxVisualizerToolWindow.cs	Removed unused GetVsService helper.
src/Razor/src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/WellKnownFeatureFlagNames.cs	Removed unused feature-flag name constants.
src/Razor/src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/VisualStudioHostServicesProvider.cs	Removed unused MEF-exported host-services provider.
src/Razor/src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/LanguageClient/Extensions/TextChangeExtensions.cs	Removed unused VS text-change conversion extension.
src/Razor/src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/Extensions/TextBufferExtensions.cs	Removed unused VS hierarchy helpers; kept only IsRazorLSPBuffer.
src/Razor/src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/Extensions/IVsHierarchyExtensions.cs	Removed unused async wrapper.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/ProjectSystem/RemoteSolutionSnapshot.cs	Removed unused GetProject(ProjectId) overload.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/ProjectSystem/RemoteSnapshotManager.cs	Simplified to parameterless construction and removed unused telemetry + code-document API.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/Completion/RazorCompletionItemResolver.cs	Removed unused override plumbing; kept static resolve entry point used by RemoteCompletionService.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/Completion/CompletionItemResolver.cs	Deleted unused abstraction.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/Completion/AggregateCompletionItemResolver.cs	Deleted unused aggregation resolver.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Remote/RazorRemoteHostClient.cs	Removed unused TryInvokeAsync overload.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/RazorSyntaxFacts.cs	Removed unused syntax helper APIs.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/RazorEventSource.cs	Removed unused event source.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Protocol/DocumentHighlight/RemoteDocumentHighlight.cs	Removed unused conversion helper.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/HostProject.cs	Deleted unused project-system model type.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/HostDocument.cs	Deleted unused project-system model type.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/FallbackRazorConfiguration.cs	Deleted unused configuration helper.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/RazorFormattingOptions.cs	Removed unused From(...) overload.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Extensions/SolutionExtensions.cs	Removed unused GetRequiredDocument helper.
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Completion/CompletionTriggerAndCommitCharacters.cs	Removed unused trigger helpers.
src/Razor/src/Razor/benchmarks/Microsoft.AspNetCore.Razor.Microbenchmarks/Formatting/DocumentFormattingBenchmark.cs	Updated to construct RemoteSnapshotManager without telemetry and inlined Razor configuration name in globalconfig text.