[CI]: Slim debian bookworm image python dockerfile (#4570)

<!-- Thanks for sending a pull request! Here are some tips for you: -->

#### What type of PR is this?

Fix

#### What this PR does / why we need it

Reduce the size for python tests so disk is not an issue in CI

Signed-off-by: Nikola Jokic <jokicnikola07@gmail.com>

Author: nikola-jokic

build/airflow-operator/Dockerfile

@@ -1,5 +1,5 @@
 ARG PLATFORM=x86_64
-ARG BASE_IMAGE=python:3.10-bookworm
+ARG BASE_IMAGE=python:3.10-slim-bookworm
 FROM --platform=$PLATFORM ${BASE_IMAGE}
 
 RUN mkdir /proto

build/python-client/Dockerfile

@@ -1,14 +1,15 @@
 ARG PLATFORM=x86_64
-ARG BASE_IMAGE=python:3.9-bookworm
+ARG BASE_IMAGE=python:3.9-slim-bookworm
 FROM --platform=$PLATFORM ${BASE_IMAGE}
 
 RUN mkdir /proto
 
+# Install dependencies for the python client including test extras
 COPY client/python/pyproject.toml /code/pyproject.toml
 
-RUN pip install "/code[test]"
+RUN pip install --no-cache-dir "/code[test]"
 
-# Creating folders, and files for a project:
+# Copy the full client sources after deps are installed for better layer reuse
 COPY client/python /code
 
 ENTRYPOINT ["/bin/bash"]