[terraform] create backup cloudwatch alarms

Summary:
This creates the backup cloudwatch alarms that were added to backup in https://phab.comm.dev/D13942

Depends on D13943

Test Plan:
Triggered alarms by including tracing error logs with each newly implemented errorType in the main.rs file in backup. Confirmed that alarms were triggered and emails were sent.

Linear issues were also created for error log alarms

Reviewers: bartek, varun

Reviewed By: bartek, varun

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D13944