perf: fine-tune autoscaling configuration

Description

This MR fine-tunes the default auto-scaling configuration for Grove-hosted edX instances.

Supporting information

(internal) discovery document: https://docs.google.com/document/d/194C20tq8Ix4Y5aBp7U7dCjXSJlmmiRvj1nsEEhMXBBw

Testing instructions

Steps to test the changes:

1. Proofread the code
2. • The rest is tested as part of load testing -

Dependencies

N/A

Screenshots

N/A

Checklist

If any of the items below is not applicable, do not remove them, but put a check in it.

• Git commit history is clean
• Git commits are following conventional-commit practices
• Unit tests are added/updated
• Documentation is added/updated

Additional context

N/A