fix: port the changes for date_to_unix_ts SQL fun from 4.4

[terry-xiaoyu]

Fixes https://emqx.atlassian.net/browse/EMQX-11929

Release version: v/e5.6.0

Port changes from https://github.com/emqx/emqx-enterprise/pull/1982.

Summary

PR Checklist

Please convert it to a draft if any of the following conditions are not met. Reviewers may skip over until all the items are checked:

• Added tests for the changes
• Added property-based tests for code which performs user input validation
• Changed lines covered in coverage report
• Change log has been added to changes/(ce|ee)/(feat|perf|fix|breaking)-<PR-id>.en.md files
• For internal contributor: there is a jira ticket to track this change
• Created PR to emqx-docs if documentation update is required, or link to a follow-up jira ticket
• Schema changes are backward compatible

Checklist for CI (.github/workflows) changes

• If changed package build workflow, pass this action (manual trigger)
• Change log has been added to changes/ dir for user-facing artifacts update

[HJianBo]

LGTM