tests: disabl should_create_tombstone_when_null_value_on_bound_statement

for scylla

This test failing on scylla:
```
java.lang.AssertionError: Did not find '1 tombstone' in trace
```

Author: dkropachev

driver-core/src/test/java/com/datastax/driver/core/PreparedStatementTest.java

@@ -775,6 +775,7 @@ public void should_not_create_tombstone_when_unbound_value_on_batch_statement_an
    * @since 2.2.0
    */
   @Test(groups = "long")
+  @ScyllaSkip
   public void should_create_tombstone_when_null_value_on_bound_statement() {
     PreparedStatement prepared =
         session().prepare("INSERT INTO " + SIMPLE_TABLE + " (k, i) VALUES (?, ?)");