[reports-service] Increase RAM and JSON payload size

Summary: Attempt to fix ENG-5682. Increased reports service payload limit to be at least MAX_REPORT_LENGTH from lib/utils/report-utils.js. Also increased service RAM to 512MB to avoid potential OOM errors.

Test Plan: None, I'll deploy this and see if it fixes the issue.

Reviewers: ashoat, michal

Reviewed By: ashoat, michal

Subscribers: tomek, wyilio

Differential Revision: https://phab.comm.dev/D9762