Do not force 32-bit on 64-bit system under VS

[nohwnd]

Description

Under VS we are running as 32-bit process which is affecting our logic that selects the correct
dotnet executor bittness based on the current process bitness and the architecture of the target
assembly. We want to run as 64-bit to choose x64 for AnyCPU assemblies when running under
VS on a 64-bit system.

But still run 32-bit when we run on 32-bit system, or when we run from 32-bit dotnet.

[nohwnd]

@Sanan07 Please review and link it to the AzDO bug you are looking into.

Tested :

C:\Projects\temp\mstest23> $env:vstest_runner_debug=1; C:\Projects\vstest\artifacts\Debug\net451\win7-x64\vstest.console.exe C:\Projects\temp\mstest23\bin\Debug\net5.0\mstest23.dll
Waiting for debugger attach...
Process Id: 828, Name: vstest.console
Microsoft (R) Test Execution Command Line Tool Version 16.8.0-dev
Copyright (c) Microsoft Corporation.  All rights reserved.

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
Testhost process exited with error: It was not possible to find any compatible framework version
The framework 'Microsoft.NETCore.App', version '5.0.0-rc.1.20371.13' was not found.
  - The following frameworks were found:
      2.1.20 at [C:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App]
      3.0.2 at [C:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App]
etc...

After change and rebuild, vstest.console correctly runs as 64-bit and chooses the correct runtime:

C:\Projects\temp\mstest23> $env:vstest_runner_debug=0; C:\Projects\vstest\artifacts\Debug\net451\win7-x64\vstest.console.exe C:\Projects\temp\mstest23\bin\Debug\net5.0\mstest23.dll
Microsoft (R) Test Execution Command Line Tool Version 16.8.0-dev
Copyright (c) Microsoft Corporation.  All rights reserved.

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
  Passed TestMethod1 [3 ms]

Test Run Successful.
Total tests: 1

[nohwnd]

This breaks QTest execution. Closing and using OSBitness instead for selecting dotnet sdk version #2507. Adding note that this would break in the csproj.