Sync eng/common directory with azure-sdk-tools for PR 7615 (#1505)

* Prepare-Release.ps1: Make dateTime.ToString("MM/dd/yyyy") to work on exotic set-ups

On my machine, I experimented with the registry, and the worst part is that I don't remember/know how to reset it back.

The work items that script produces, do have datetimes for the upcoming releases in the `MM-dd-yyyy` format, and then I have to correct them by hand.

`dateTime.ToString("MM/dd/yyyy")` does produce the date in the format of `MM-dd-yyyy` on my machine. This also happens if I write a corresponding .NET app.

The fix that I am proposing makes it work on my specific setup and hopefully breaks no one else. I understand if you are hesitant to take it. Let me know, I'll see how I can restore my setting.

But on the other hand, I don't think it makes anything worse, it only makes things more robust, so maybe take it?

* Use [CultureInfo]::InvarialtCulture

Co-authored-by: Wes Haggard <weshaggard@users.noreply.github.com>

* Update eng/common/scripts/Prepare-Release.ps1

* Update eng/common/scripts/Prepare-Release.ps1

---------

Co-authored-by: Anton Kolesnyk <41349689+antkmsft@users.noreply.github.com>
Co-authored-by: Wes Haggard <weshaggard@users.noreply.github.com>

eng/common/scripts/Prepare-Release.ps1

@@ -109,7 +109,8 @@ else
   $ParsedReleaseDate = [datetime]$ReleaseDate
 }
 
-$releaseDateString = $ParsedReleaseDate.ToString("MM/dd/yyyy")
+# Use InvariantCulture so that the date format is consistent on all machines
+$releaseDateString = $ParsedReleaseDate.ToString("MM/dd/yyyy", [CultureInfo]::InvariantCulture)
 $month = $ParsedReleaseDate.ToString("MMMM")
 
 Write-Host "Assuming release is in $month with release date $releaseDateString" -ForegroundColor Green