CiviTestListener - Headless tests should have initialized timezone

Before
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* `CiviUnitTestCase` calls `setMySQLTimeZone()`
* Headless tests (which are initialized via `CiviTestListener`) do not call `setMySQLTimeZone()`
* If you have a test like 5.57's flavor of `QueueTest`, then the tests pass or fail depending on happenstance of server timezone configuration.

After
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* `CiviUnitTestCase` and `CiviTestListener` both call `setMySQLTimeZone()`
* If you have a test like 5.57's flavor of `QueueTest`, then the tests pass more consistently.

Comments
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This branch should work cleanly as PR for `5.59` (rc) or `master`.  I'd
rather like to use this in `5.57-esr` (so that tests run more cleanly).
So maybe `5.59` is the better target (but it doesn't strictly have to be).