fix the agentimage that we compare to on linux to allow our osname to pass through properly

Author: scbedd

eng/common/scripts/Verify-AgentOS.ps1

@@ -10,7 +10,7 @@ function Throw-InvalidOperatingSystem {
 
 if ($IsWindows -and $AgentImage -match "windows|win|MMS\d{4}") {
     $osName = "Windows"
-} elseif ($IsLinux -and $AgentImage -match "ubuntu") {
+} elseif ($IsLinux -and $AgentImage -match "ubuntu|linux") {
     $osName = "Linux"
 } elseif ($IsMacOs -and $AgentImage -match "macos") {
     $osName = "macOS"