It is possible for toStartOfMinute() to give different result for 0 and
59, for partial timezones (timezone that does not starts from 00:00,
like Africa/Monrovia).
Before #36656 it fails for another reason, because of overflows [1], but
now it fails because it simply return different minutes.
[1]: https://github.com/ClickHouse/ClickHouse/pull/29953#discussion_r800550280
Simply pin the UTC there.
Fixes: #37786
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>