Fix URL base of API endpoint

What does this MR do and why?

The VSA dashboard's filter bar breaks at group level because the URLs which represent an API endpoint do not use groups/ prefix like the controller endpoints do. So fullPath is too long.

How to set up and validate locally

See reproduction steps in #396981 (closed).

Before

(in network tab of inspector)

After

(in network tab of inspector)

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #396981 (closed)