discovery: remove a potential memory leak
discovery: remove a potential memory leak

   Remove a potential memory leak when deleting an element from a slice.

Change-Id: Ib5ff2802d9e9b1b077cc8f8716f49e526ab4b801

vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref