Increase Solr heap size in production

[hancush]

Overview

See title. There is a detailed discussion of why I did this in #538.

For reference, the Metro server is a t2 large EC2 instance:

Checklist

• PR has a descriptive enough title to be useful in changelogs

Testing Instructions

• Start the production Solr instance locally: docker-compose -f docker-compose.deployment.yml up solr-production
• Navigate to http://localhost:8985/solr/ and confirm the JVM Memory is 1 GB (or in that neighborhood – sometimes it's a little less, e.g., mine is 981 MB).

Handles #538

[jeancochrane]

Works as advertised! I left some questions for future investigations in #538 (comment) but I think this is ready to come in as a stopgap measure.