Remove the temporary NetCoreSdkRoot drive-casing MSB4216 workaround once the msbuild fix reaches the supported VS + SDK floor (#17039)

[AlesProkop]

Tracking issue to delete the temporary workaround added in #17039 (builds on #17002).

It compensates for the case-sensitive .NET task host handshake salt. The permanent fix is bilateral and ships outside Arcade:

• dotnet/msbuild#14026 — root cause (OPEN)
• dotnet/msbuild#14027 — permanent child-side salt widening (OPEN)

Remove when: the minimum VS and minimum .NET SDK versions used across Arcade-consuming CI both carry the salt normalization (not merely when the msbuild issues close).

Acceptance criteria

• Delete the NormalizeNetCoreSdkRootCasing target, the NormalizeSdkRootDriveCasing task, and the two knobs from Workarounds.targets.
• Restore the bare <Project> root (drop InitialTargets="NormalizeNetCoreSdkRootCasing").
• Confirm MSB4216 does not recur on the affected ADO/CodeQL agents (e.g. the microsoft-testfx CodeQL pipeline used to validate Fix #14026 NET task host MSB4216 via dotnet-host drive-casing probe (builds on #17002) #17039).
• Close/supersede Replace the inline drive-casing probe in Workarounds.targets with a maintainable, tested implementation #17051 if still open.

Trigger / watch: dotnet/msbuild#14026, dotnet/msbuild#14027, and their availability in shipped VS + .NET SDK.