rust/protover: remove redundant test

commit 15e59a1fed added a test
for parsing an empty string twice.

src/rust/protover/protover.rs

@@ -874,11 +874,6 @@ mod test {
         assert_protoentry_is_unparseable!("Desc=1-4294967295");
     }
 
-    #[test]
-    fn test_protoentry_from_str_() {
-        assert_protoentry_is_unparseable!("");
-    }
-
     #[test]
     fn test_protoentry_all_supported_single_protocol_single_version() {
         let protocol: UnvalidatedProtoEntry = "Cons=1".parse().unwrap();