PowerShell update checker ignores `POWERSHELL_UPDATECHECK` environment variable

System Details

System Details Output

### VSCode version: 1.53.2 622cb03f7e070a9670c94bae1a45d78d7181fbd4 x64

### VSCode extensions:
azsdktm.SecurityIntelliSense@0.8.0     
AzurePolicy.azurepolicyextension@0.1.1 
DotJoshJohnson.xml@2.5.1
eamodio.gitlens@11.2.1
everettjf.filter-line@2.0.1
jinsihou.diff-tool@0.0.1
ms-azure-devops.azure-pipelines@1.183.0
ms-azuretools.vscode-azureappservice@0.21.0
ms-azuretools.vscode-azureresourcegroups@0.3.0
ms-dotnettools.vscode-dotnet-runtime@1.0.0
ms-vscode.azure-account@0.9.6
ms-vscode.powershell@2021.2.2
msazurermtools.azurerm-vscode-tools@0.14.1
ryu1kn.text-marker@1.11.0
Summer.azure-event-hub-explorer@0.1.2


### PSES version: 2.3.0.0

### PowerShell version:

Name                           Value
----                           -----
PSVersion                      7.0.5
PSEdition                      Core
GitCommitId                    7.0.5
OS                             Microsoft Windows 10.0.19042
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}       
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Issue Description

I am experiencing a problem with… VS Code notifies as follows…

You have an old version of PowerShell (7.0.5). The current latest release is v7.1.2. Would you like to update the version? (This will close ALL pwsh terminals running in this Visual Studio Code session)

However I have set $Env:POWERSHELL_UPDATECHECK to “LTS” per https://docs.microsoft.com/en-us/powershell/scripting/whats-new/what-s-new-in-powershell-70?view=powershell-7.1#new-version-notification

Expected Behaviour

I’d expect the notification to only appear when updates to the LTS version of Powershell 7 are available. EG: 7.0.6.

Actual Behaviour

VS Code notifies as follows…

You have an old version of PowerShell (7.0.5). The current latest release is v7.1.2. Would you like to update the version? (This will close ALL pwsh terminals running in this Visual Studio Code session)

Attached Logs

Follow the instructions in the [troubleshooting docs](https://github.com/PowerShell/vscode-powershell/blob/master/docs/troubleshooting.md#logs vscode-powershell.zip vscode-powershell.zip

) about capturing and sending logs.

[SydneyhSmith]

Thanks @trolleyboy VSCode does not check for this variable when it runs its update mechanism, but this is a reasonable feature request to add a check for…thanks for catching and reporting this!

[JustinGrote]

No I’m saying we should have tests to confirm that if we fix it 😃