Add regions for high side AWS Gov Cloud

⚠ ️NOTE THAT THIS FORK IS MAINTAINED FOR CRITICAL BUG FIXES AFFECTING RUNNING COSTS ONLY. NO OTHER CONTRIBUTIONS WILL BE ACCEPTED. ⚠️

What critical bug this MR is fixing?

There are AWS regions missing that customers have to use.

How does this change help reduce cost of usage? What scale of cost reduction is it?

In what scenarios is this change usable with GitLab Runner's docker+machine executor?

This change allows gov customers to leverage scaling runners, via docker machine in AWS gov cloud classified environments.