Postgis cleanup

[SpacemanPaul]

Reason for this pull request

Cleanup and refactor of postgis index driver and cross-driver tests. Motivated by need for new EO3-only lineage implementation.

Proposed changes

• Remove from postgis driver the old implementation inherited from legacy driver for adding lineage in the dataset add.

• Resulting refactor of tests motivated by above.

• NB Remaining minor test coverage drop mostly due to removal of (covered) code.

• Tests added / passed

• Fully documented, including docs/about/whats_new.rst for all changes

---

📚 Documentation preview 📚: https://datacube-core--1368.org.readthedocs.build/en/1368/

[codecov]

Codecov Report

Base: 92.75% // Head: 92.70% // Decreases project coverage by -0.05% ⚠️

Coverage data is based on head (6e069b5) compared to base (5c42f81).
Patch coverage: 90.90% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1368      +/-   ##
===========================================
- Coverage    92.75%   92.70%   -0.06%     
===========================================
  Files          130      130              
  Lines        13627    13607      -20     
===========================================
- Hits         12640    12614      -26     
- Misses         987      993       +6     

Impacted Files	Coverage Δ
datacube/scripts/dataset.py	89.41% <ø> (+0.27%)	⬆️
datacube/index/postgis/_datasets.py	71.14% <90.90%> (-1.80%)	⬇️
datacube/drivers/postgis/_api.py	85.60% <0.00%> (-1.52%)	⬇️

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[SpacemanPaul]

Superseded by #1372