chore: add Pkg sources to test envs, switch draft backend testing to -O1

[gdalle]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.64%. Comparing base (5a3ea38) to head (adddf6e).

❗ There is a different number of reports uploaded between BASE (5a3ea38) and HEAD (adddf6e). Click for more details.

HEAD has 43 uploads less than BASE

Flag	BASE (5a3ea38)	HEAD (adddf6e)
DI	52	17
DIT	12	4

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1002       +/-   ##
===========================================
- Coverage   98.21%   87.64%   -10.57%     
===========================================
  Files         135      132        -3     
  Lines        8000     7947       -53     
===========================================
- Hits         7857     6965      -892     
- Misses        143      982      +839     

Flag	Coverage Δ
DI	86.80% <ø> (-12.18%)	⬇️
DIT	89.83% <ø> (-6.40%)	⬇️

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.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.