[keyserver] Call setupDB from DB migration if meta table is missing

Summary:
Depends on D4150

Linear task: ENG-1208

Test Plan:
Create a keyserver/.env file, eg.:

COMM_MYSQL_DATABASE=commdev
COMM_MYSQL_USER=commdev
COMM_MYSQL_PASSWORD=pass

And then run the Docker image: cd keyserver && docker-compose down -v && docker-compose up --build

It should successfully connect to MySQL and start all of its threads. At this point (for the first time) Node should stop crash looping.

Reviewers: palys-swm, atul

Reviewed By: palys-swm, atul

Subscribers: Adrian, yayabosh

Differential Revision: https://phabricator.ashoat.com/D4151