Fix typo for omitZero in database.go from PR #6492 (#6515)
Fix typo for omitZero in database.go from PR #6492 (#6515)

We have a new method, omitZero, which is to allow `max_statement_time`
and `long_query_time` to be zeroed out, but copy/paste error left
`long_query_time` out. Fix it.
letsencrypt/boulder,letsencrypt/boulder,letsencrypt/boulder