[vs17.8] Recover bootstrap and corresponding disabled tests

[GangWang01]

partially fix #11888

Context

Previously before disabling bootstrap build on Windows Full in CI pipeline failed with mismatched dependency version. It's caused by that for bootstrap the additional assemblies copied from VS 17.14 in the image windows-2022 has higher version than this release branch.

Changes Made

Force to use XCopyMsbuild for bootstrap on Windows Full in CI pipeline to avoid additional assemblies copied from VS installation which may mismatch the version.

Testing

N/A

Notes

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[Copilot]

Pull Request Overview

This PR re-enables bootstrap builds and previously disabled tests that were failing due to dependency version mismatches on Windows Full framework in the CI pipeline. The fix forces the use of XCopyMsbuild for bootstrap builds to avoid conflicts with VS assemblies.

• Re-enables bootstrap build functionality that was previously disabled due to CI failures
• Restores previously skipped tests by removing skip attributes and adding appropriate framework-specific test attributes
• Updates CI configuration to force XCopyMsbuild usage on Windows Full framework

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/Tasks.UnitTests/ResourceHandling/GenerateResource_Tests.cs	Re-enables two test methods by replacing skip attributes with WindowsFullFrameworkOnlyFact
src/Tasks.UnitTests/ResourceHandling/GenerateResourceOutOfProc_Tests.cs	Re-enables two test methods by removing skip attributes
src/Tasks.UnitTests/MSBuild_Tests.cs	Re-enables PropertyOverridesContainSemicolon test by removing skip attribute
src/Build.UnitTests/EscapingInProjects_Tests.cs	Re-enables eight test methods by removing skip attributes
src/Build.UnitTests/BackEnd/MSBuild_Tests.cs	Re-enables PropertyOverridesContainSemicolon test by removing skip attribute
eng/cibuild_bootstrapped_msbuild.sh	Updates bootstrap build script to enable bootstrap creation and adds stage 2 build execution
eng/cibuild_bootstrapped_msbuild.ps1	Significantly expands PowerShell script to add complete stage 2 bootstrap build functionality
eng/Versions.props	Updates version prefix from 17.8.34 to 17.8.35
.vsts-dotnet-ci.yml	Adds ForceUseXCopyMSBuild environment variable to CI configuration