Add missing timezone when copying legacy artifacts (ci_builds)

What does this MR do?

Honor the timezone for timestamps in ci_builds when copying to ci_job_artifacts when the database is PostgreSQL and the timezone is not UTC.

This MR is a result of my attempt to get the spec:unit tests running locally in their entirety

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• Documentation created/updated or ~follow-up review issue created~~
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

The behavior of this feature is incorrect, since it copies timestamps with the incorrect timestamp to ci_job_artifacts when the database timezone is NOT UTC. Is this behavior documented

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• ~~Label as security and @ mention~~ @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team