[terraform] Adds aws region export to aws-deploy.sh script

Summary:
Ashoat ran into an issue of having a different aws region configured through aws-cli when running aws-deploy which prevented the migrations from running.

We should ensure the script properly sets the region so the user will always be able to run the script

Depends on D12930

Test Plan:
I deployed my self-host setup to us-east-1. Through aws configure, I set the region to us-east-2 and ensured the aws-cli region was set by using aws-cli to
describe the keyserver cluster which resulted in a non-existent cluster. However, the script works properly, demonstrating that the script was able to properly
set the region to us-east-1

Reviewers: bartek, varun

Reviewed By: bartek

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12959