Fix crash: correct Waitress param name (clear_untrusted_proxy_headers)

clear_untrusted isn't a real Adjustments option -- caused the previous
deploy to crash-loop smb-crm. The real option, clear_untrusted_proxy_headers,
already defaults to True, so it doesn't need to be passed at all.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backoffice/app/app.py

@@ -422,5 +422,4 @@ if __name__ == "__main__":
     # only thing that can dial us at all is Caddy on the shared `proxy`
     # Docker network -- trusting "*" here doesn't widen who can reach us.
     serve(app, host="0.0.0.0", port=8080, trusted_proxy="*",
-          trusted_proxy_headers={"x-forwarded-for", "x-forwarded-proto", "x-forwarded-host"},
-          clear_untrusted=True)
+          trusted_proxy_headers={"x-forwarded-for", "x-forwarded-proto", "x-forwarded-host"})