[DBAgentTest] Prepare to fix dbAgentTestUpsertWithPrimaryKeyAutoInc().

dbAgentTestUpsertWithPrimaryKeyAutoInc() checks that a value in
column with the primary key is kept. However, the target table:
COLUMN_DEF_TEST doesn't have the flag: SQL_COLUMN_FLAG_AUTO_INC.

This patch is a preparaton of the fix in which
dbAgentTestUpsertWithPrimaryKeyAutoInc() uses COLUMN_DEF_TEST_AUTO_INC.