Fix BIT + Etc/ timezones

[Zephyrkul]

According to the adjacent comment (and Wikipedia), Baker Island is UTC−12. However, the timezone passed is incorrectly set to Pacific/Funafuti, a timezone of Tuvalu, which is on the other side of the International Date Line from Baker Island (and thus UTC+12). This PR sets BIT to Etc/GMT+12, which is UTC−12.

The other Etc/ timezones have also been fixed, as the signs for the Etc/ area are flipped from ISO conventions. ([cite 1], [cite 2])

[Zephyrkul]

black is failing on this PR but this is due to files in other areas of the repo (ccrole/ccrole.py and fifo/task.py, specifically) - the only file this PR touches would not be reformatted.