Powershell: Two module tests were failing on 2016 and 2019 in release automation test run

[daxian-dbw]

PSModulePath changes interacting with other PowerShell processes. - Does not duplicate the System32 module path in subprocesses in test\powershell\Modules\Microsoft.PowerShell.Core\CompatiblePSEditions.Module.Tests.ps1
SxS Module Path Basic Tests. - Ensures $PSHOME\Modules is inserted correctly when launched from a different version of PowerShell in test\test\powershell\engine\Module\ModulePath.Tests.ps1

They failed in the automation test run, but both passed when running them manually on a 2019 VM, so not exactly sure why they were failing.

[iSazonov]

If there are two (or more) processes running they can both write to PSModulePath env.

[daxian-dbw]

We are not running our Pester tests in parallel, also a process only writes to the process scope PSModulePath env variable, so there is not race condition between processes.

[anmenaga]

Previously, I've seen failures in Does not duplicate the System32 module path in subprocesses in CI.
Could not repro locally, but it definetely failed in CI before. I've added some diagnostics to a branch based off RC1 branch; we'll see if we get more info on what is going on...