[Fixtures] USA deleted from the World zone

[TheMilek]

Q	A
Branch?	1.10
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
License	MIT

USA being a part of 2 zones at once was misleading with the concept of actual work predicted for zones and was causing some problems when calculating taxes for this country in case this 2 zones had different taxes.

[lchrusciel]

The base of this pull-request was changed, you need fetch and reset your local branch
if you want to add new commits to this pull request. Reset before you pull, else commits
may become messed-up.

Unless you added new commits (to this branch) locally that you did not push yet,
execute git fetch origin && git reset "fixtures-for-zones-with-taxes" to update your local branch.

Feel free to ask for assistance when you get stuck 👍

[lchrusciel]

Thanks, Kamil! 🎉