Fix DB2 column 'id' autoincrement issue

After installing heat against DB2, we can't insert data in table
event, the reason is that "event_table.c.tmp_id.alter(
sqlalchemy.Integer, autoincrement=True)" can't make sense after
above "tmp_id=>id" transformation, Now need work around it.

Change-Id: I50025fc5db87d458e660d42c773d799fc36f1b27
Closes-Bug: #1316041
Merge "Fix DB2 column 'id' autoincrement issue"