* Fix test galera.MW-44 to make it work with --ps-protocol
* Skip test galera.MW-328C under --ps-protocol This test
  relies on wsrep_retry_autocommit, which has no effect
  under ps-protocol.
* Return WSREP related errors on COM_STMT_PREPARE commands
  Change wsrep_command_no_result() to allow sending back errors
  when a statement is prepared. For example, to handle deadlock
  error due to BF aborted transaction during prepare.
* Add sync waiting before statement prepare
  When a statement is prepared, tables used in the statement may be
  opened and checked for existence. Because of that, some tests (for
  example galera_create_table_as_select) that CREATE a table in one node
  and then SELECT from the same table in another node may result in errors
  due to non existing table.
  To make tests behave similarly under normal and PS protocol, we add a
  call to sync wait before preparing statements that would sync wait
  during normal execution.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>