Revert MSBUILDSINGLELOADCONTEXT

This reverts commit 3f5392e, but leaves
the SDK at 3.1.201.

Author: rainersigwald

.github/workflows/build.yml

@@ -16,7 +16,6 @@ on:
 
 env:
   DOTNET_ROLL_FORWARD_ON_NO_CANDIDATE_FX: 2
-  MSBUILDSINGLELOADCONTEXT: 1
   ENABLED_MULTI_STAGE_BUILD: true
   ENABLED_UNIT_TESTS: true
   ENABLED_PUBLISH_DOCKER: true

azure-pipelines.yml

@@ -12,7 +12,6 @@ pr:
 variables:
   DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 'true'
   DOTNET_CLI_TELEMETRY_OPTOUT: 'true'
-  MSBUILDSINGLELOADCONTEXT: 1
 
 stages:
 - stage: Build

build/utils/docker.cake

@@ -126,15 +126,13 @@ DockerContainerRunSettings GetDockerRunSettings(BuildParameters parameters)
         settings.Env = new[]
         {
             "TF_BUILD=true",
-            "MSBUILDSINGLELOADCONTEXT=1",
             $"BUILD_SOURCEBRANCH={Context.EnvironmentVariable("BUILD_SOURCEBRANCH")}"
         };
     }
     if (parameters.IsRunningOnGitHubActions) {
         settings.Env = new[]
         {
             "GITHUB_ACTIONS=true",
-            "MSBUILDSINGLELOADCONTEXT=1",
             $"GITHUB_REF={Context.EnvironmentVariable("GITHUB_REF")}"
         };
     }