This is a followup of MDL-76674 (the last case that has happened), and a myriad of similar issues, all them related to the inclusion or renaming of some TZ name.

The problem is that those changes happen too often (say 5-10 times every year, each time that the IANA TZ database is updated).

And, such a simple problem makes tests to fail everywhere! GHA, CI, local dev environments...

So this issue is about:

1. Make the current tests to stop looking, on every execution for ALL the timezones existence, just checking for a few, stable ones. So, normal runs out there won't become affected).
2. Be able to, via opt-in configuration, force the check of ALL the timezones to happen.
3. Ensure that the ALL timezones check is running somewhere, so we get informed ASAP.
4. (Only if the previous point is not enough): Prospect some system, ideally automatic, able to warn us about changes ASAP (maybe a subscription to IANAs TZ announces...).

I've put the 4th point as optional because, in the last case (MDL-76674)... we have started to detect the problems as of today (December 14th 2022) in GHA runs. And the last update (and availability) of the updated TZ data was November 29th 2022). See both the release and the availability of the PECL package:

• Announce (2022g): http://mm.icann.org/pipermail/tz-announce/2022-November.txt (Nov 29th).
• PECL release (2002.7): https://pecl.php.net/package/timezonedb (immediate, Nov 29th).

So, if we are able to detect the changes by continuously updating the timezonedb and running ALL tests, that will give us some good time to proceed with the updates before affecting to anybody (specially if "anybody" is unaffected, because of the point #1 of the plan - just run a subset normally).

Ciao