[terraform] add PITR to dynamodb tables

Summary: enabled point in time recovery for all tables except identity workflows and nonces. wasn't sure which tables for other services should have this feature so enabled for all of them

Test Plan: confirmed with terraform plan that these changes would enable PITR in production only

Reviewers: bartek, kamil

Reviewed By: bartek

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D13203