Set instance ID from pod:container and let setting metadata from annotations

[mariomac]

Fixes the way the instance ID is composed. This means that instanceID is not assured to be globally unique anymore, but the service_name/namespace/instance tuple. This required changing some internals about how we use the svc.ID and svc.UID types.

Also, lets overriding the service metadata by means of user-selected pod labels.

This PR also seems to fix (or at leas decrease) a memory leak that was present in the Store, by changing the way that containers are grouped by owner and deleted.

TODO:

• Integration tests
• Documentation (to be handled into another PR)

[codecov]

Codecov Report

Attention: Patch coverage is 93.33333% with 8 lines in your changes missing coverage. Please review.

Project coverage is 81.10%. Comparing base (66b1975) to head (6350aef).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/kubecache/meta/informers_init.go	33.33%	6 Missing ⚠️
pkg/internal/request/span_getters.go	80.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1391      +/-   ##
==========================================
+ Coverage   72.44%   81.10%   +8.65%     
==========================================
  Files         146      146              
  Lines       14742    14731      -11     
==========================================
+ Hits        10680    11947    +1267     
+ Misses       3361     2203    -1158     
+ Partials      701      581     -120     

Flag	Coverage Δ
integration-test	58.68% <41.66%> (-0.18%)	⬇️
k8s-integration-test	60.11% <85.83%> (+0.05%)	⬆️
oats-test	34.08% <19.16%> (-0.16%)	⬇️
unittests	51.87% <67.50%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles