Reject "OR REPLACE ... IF NOT EXISTS" in the grammar
Reject "OR REPLACE ... IF NOT EXISTS" in the grammar

The parser now rejects having both OR REPLACE and IF NOT EXISTS in the
same statement.

Signed-off-by: Rafael Ávila de Espíndola <1975039f9046bf513b77c0c5639a0efc25f00e7f@scylladb.com>

avikivity/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla