Add a "memory.hint" parameter to Aphlict

Summary:
Ref T10696. By default, node uses 1.5GB, which is enormous overkill for this service and can crowd out other services if it's running next to things like a database on the same host.

Provide a configuration option to adjust it via --max-old-space-size and default to 256MB. It only seems to need about 30M locally, so this should be plenty of headroom.

Test Plan:
Ran bin/aphlict debug, things seemed OK.

It takes a long time (days?) to grow to 1.5GB so I can't easily test this locally without a lot of work, but I'll keep an eye on it in production.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10696

Differential Revision: https://secure.phabricator.com/D15720