Make test robust

images/ubuntu/scripts/tests/System.Tests.ps1

@@ -10,11 +10,11 @@ Describe "Disk free space" -Skip:(-not [String]::IsNullOrEmpty($env:AGENT_NAME)
 Describe "fwupd removed" {
     It "Is not present on box" {
         $systemctlOutput = & systemctl list-unit-files fwupd-refresh.timer
-        if ($systemctlOutput -eq $null) {
-            # Service not installed, test passes
-            return
-        } else {
-            $systemctlOutput | Should -Match "masked"
-        }
+        # When enabled the output looks like this:
+        #❯ systemctl list-unit-files fwupd-refresh.timer
+        #UNIT FILE           STATE   VENDOR PRESET
+        #fwupd-refresh.timer enabled enabled
+        #1 unit files listed.
+        $systemctlOutput | Should -Not -Match "enabled"
     }
 }