Revert "DOTNET_CLI_DO_NOT_USE_MSBUILD_SERVER=true in yaml?"

This reverts commit 3f3c9c0.

Author: jonathanpeppers

build-tools/automation/yaml-templates/variables.yaml

@@ -35,6 +35,3 @@ variables:
   value: net7.0
 - name: DotNetStableTargetFramework
   value: net6.0
-# Workaround: https://github.com/dotnet/sdk/issues/26965
-- name: DOTNET_CLI_DO_NOT_USE_MSBUILD_SERVER
-  value: true