[Windows] Refactor PATH helpers (#8885)

images/windows/scripts/tests/Helpers.psm1

@@ -6,18 +6,6 @@ function Get-EnvironmentVariable($variable) {
     return [System.Environment]::GetEnvironmentVariable($variable, "Machine")
 }
 
-# Update environment variables without reboot
-function Update-Environment {
-    $variables = [Environment]::GetEnvironmentVariables("Machine")
-    $variables.Keys | ForEach-Object {
-        $key = $_
-        $value = $variables[$key]
-        Set-Item -Path "env:$key" -Value $value
-    }
-    # We need to refresh PATH the latest one because it could include other variables "%M2_HOME%/bin"
-    $env:PATH = [Environment]::GetEnvironmentVariable("PATH", "Machine")
-}
-
 function Invoke-PesterTests {
     <#
     .SYNOPSIS