cql3: Kill unimplemented query_options constructor
cql3: Kill unimplemented query_options constructor

The constructor was added in commit 7f3ce39 ("query_options: Add
constructor for batch mode options (multi-level)") but apparently it was
never actually implemented.

Spotted by CLion.
Message-Id: <412f720c79320b8d85a8bae1d2c0d1ee03da3db9@scylladb.com>

avikivity/scylla,duarten/scylla,duarten/scylla,scylladb/scylla,raphaelsc/scylla,scylladb/scylla,avikivity/scylla,raphaelsc/scylla,raphaelsc/scylla,duarten/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla