Do not show timezone offset notification when user setting is UTC
Summary:
Telling users with a UTC timezone setting in the user preferences twice a year (if you are in a place which has a Daylight Saving Time regime) that "Your browser timezone differs from your profile timezone", or even more than twice a year if you travel, makes no sense.
Do not show that message if the user's Timezone setting is UTC, because UTC is not bound to a location. The user does not care about the timezone offset as they chose UTC.
Prior work: rP8092d90c
Closes T16255
Test Plan:
# Make sure your browser has a timezone set which is not UTC
# As an admin, go to http://phorge.localhost/config/edit/phabricator.timezone/ and set Default Timezone to "UTC"
# As an admin, create two new users tztesting01 and tztesting02 via http://phorge.localhost/people/create/
# Log in as tztesting01, see "Your browser timezone setting differs from the timezone setting in your profile, click to reconcile." notification
# Apply patch
# Log in as tztesting02, do not see "Your browser timezone setting differs from the timezone setting in your profile, click to reconcile." notification
Bonus exercise: Try with a different default timezone (I have not).
When testing, also note that `PhabricatorTimezoneSetting::expandSettingTransaction()` clears any ignored timezone offset.
Reviewers: O1 Blessed Committers, mainframe98
Reviewed By: O1 Blessed Committers, mainframe98
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Maniphest Tasks: T16255
Differential Revision: https://we.phorge.it/D26319