[main] Source code updates from dotnet/dotnet (#19131)

* Backflow from https://github.com/dotnet/dotnet / 29eefe2 build 293166

[[ commit created by automation ]]

* Update dependencies from https://github.com/dotnet/dotnet build 293166
No dependency updates to commit

---------

Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>

Author: dotnet-maestro[bot]

eng/Version.Details.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Dependencies>
-  <Source Uri="https://github.com/dotnet/dotnet" Mapping="fsharp" Sha="cc7f6e84d8dae36ad9ea51a5112627b8235982cc" BarId="291900" />
+  <Source Uri="https://github.com/dotnet/dotnet" Mapping="fsharp" Sha="29eefe27a350eb8b0bcbababa7863a0d1086295d" BarId="293166" />
   <ProductDependencies>
     <Dependency Name="Microsoft.Build" Version="18.1.0-preview-25515-01">
       <Uri>https://github.com/dotnet/msbuild</Uri>

start-vs-FsharpSln.cmd

@@ -7,9 +7,6 @@ setlocal enabledelayedexpansion
 set DOTNET_ROOT=%~dp0.dotnet
 set DOTNET_ROOT(x86)=%~dp0.dotnet\x86
 
-:: This tells .NET Core not to go looking for .NET Core in other places
-set DOTNET_MULTILEVEL_LOOKUP=0
-
 :: Put our local dotnet.exe on PATH first so Visual Studio knows which one to use
 set PATH=%DOTNET_ROOT%;%PATH%