Fix broken CI image optimisation

[potiuk]

The commit 5918efc broke
optimisation of the CI image - using the Apache Airflow
master branch as base package installation source from pypi.

This commit restores it including removal of the
obsoltete CI_OPTIMISED arg - as now we have a separate
production and CI image and CI image is by default
CI_OPTIMISED

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[potiuk]

The 3.8 commit added +10 minutes for rebuild time whenever setup.py changes - both in CI and Breeze, so we better fix it .

[potiuk]

I'd love to get that one fixed. It makes local rebuilds for changed setup run much slower than it should currently it always reinstalls all dependencies always from 0 which adds a lot of time for rebuilds/