Allow registering multiple runners at the group namespace level with a single helm chart

Description

Feature Request: Allow registering multiple runners at the group namespace level with a single helm chart.

Proposal

My use case is setting up shared GitLab CI runners for multiple teams on my company's GitLab install and I need to register multiple runners to allow teams to request appropriate CPU/Memory for their CI build jobs. I would like to be able to do that in the existing Helm chart instead of having to vendor it and add my own modifications.

Links to related issues and merge requests / references

See notes from closed Runner issue here: #3717 (closed)