Reduce analytics devkit reviewers from 2 to 1

Reduces reviewers assigned to Analytics Devkit RenovateBot MRs from 2 to 1.

This is because the majority of dependency updates are minor/patch and don't impact our project in any way. Having a single reviewer will help us be more efficient and get these updates through quicker. We still have a 2nd safety net to catch issues in that these updates still need to be applied to analytics-stack before any issues could hit customers.

We had 2 assigned as that is the default config provided in this renovatebot helper project, so it wasn't necessarily ideal for us to begin with. Several other projects already use reviewer size 1 for renovate MRs (container registry, gitlab pages, customers, gitlab shell, etc).