WL#9218: Remove deprecated LOAD DATA events from replication code

LOAD_EVENT, CREATE_FILE_EVENT, EXEC_LOAD_EVENT and NEW_LOAD_EVENT were binlogged
for LOAD DATA  statement. But they has been deprecated since MySQL-5.0.3.
BEGIN_LOAD_QUERY_EVENT and EXECUTE_LOAD_QUERY_EVENT were introduced for
convenient. For cross version compatibility, we just kept the code. According to
our support policy, we can remove them from 8.0 To keep the code simple and
readable, we should do that.