src: Remove image-builder.users.enabled flag

The Users customization is available in production now, the flag is no longer used.

src/test/Components/CreateImageWizard/steps/Oscap/Compliance.test.tsx

@@ -52,6 +52,7 @@ const goToReviewStep = async () => {
   await clickNext(); // Snapshots
   await clickNext(); // Custom repositories
   await clickNext(); // Additional packages
+  await clickNext(); // Users
   await clickNext(); // Timezone
   await clickNext(); // Locale
   await clickNext(); // Hostname