rtl_test opens the USB device during probing. After killing the
process, the kernel may not release the USB interface immediately.
dump1090 then fails with usb_claim_interface error -6. Add a 0.5s
delay after probe cleanup to allow the kernel to fully release the
device before the actual decoder opens it.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>