Ability to set bucket prefix for object storage

[fsiler]

Is your feature request related to a problem? Please describe.

I am in an environment where it's annoying to create storage buckets. I have observability set up to store related data in a bucket- /observability1/traces, /observability1/metrics, and so on. I need the ability to set Pyroscope to use eg /observability1/pyroscope within a bucket

Describe the solution you'd like

A prefix setting inside the objstore config. Thanos, Tempo, and Loki all support this. I've tried a few iterations and looked through the source, and I don't find where this parameter would be located.

Describe alternatives you've considered

This is just a missing setting, and arguably closer to a bug than a feature request.

Additional context

n/a

[simonswine]

It is possibile today, you might have missed it because it is marked as experimental, I do think we can graduate that bit:

pyroscope/cmd/pyroscope/help-all.txt.tmpl

Lines 960 to 961 in 3da96b8

	-storage.storage-prefix string
	[experimental] Prefix for all objects stored in the backend storage. For simplicity, it may only contain digits and English alphabet letters.

We also recently had a validation bug, and there fore the help message is inaccurate. Will update both shortly