drop workaround for Chrome bug causing `Intl.DateTimeFormat` + `Factory` timeZone to throw error

The following can be removed once https://issues.chromium.org/issues/381620359 is fixed and stable for a few releases:

* https://github.com/jcfranco/timezone-groups/commit/c54658b2369a469d57c20dd72497ea787a22d856
* https://github.com/jcfranco/timezone-groups/commit/dc84ecab6ed7805679fc8b0792f6bfcd1309a9e0