Add profiles' self-scraping support

[michaeldmitry]

Issue

Fixes #388
Fixes #384

Solution

Add a self-scraping config if no remote parca instance is connected over self-profiling-endpoint

Drive-bys

remove observability_libs/juju_topology.py from parca_scrape.py

Testing Instructions

1.juju deploy grafana-k8s grafana --channel edge --trust
2. Deploy this parca parca0
3. Deploy another app parca1
4. juju integrate parca0 grafana:grafana-source
5. juju integrate parca1 grafana:grafana-source
6. Open Grafana UI
7. Go to parca0 source -> you should see parca0's own profiles
8. Go to parca1 source -> you should see parca1's own profiles
9. juju integrate parca0:self-profiling-endpoint parca1
10. Open Grafana UI
11. Go to parca0 source -> you should not see parca0's own profiles
12. Go to parca1 source -> you should see parca1's own profiles as well as parca0's profiles

[PietroPasotti]

some refactoring needed

[PietroPasotti]

little bit of cleanup needed, rest looks ok!
Wonder if we should wait for #391 to merge first or the other way around

[michaeldmitry]

little bit of cleanup needed, rest looks ok! Wonder if we should wait for #391 to merge first or the other way around

let's merge #391 first

[PietroPasotti]

couple of changes necessary

[PietroPasotti]

LGTM!