fix: switch some python:3 images to use the -slim variant #1972

Job	Run time
ci (kubernetes, ./tests/bin/ci.sh -e 'test(7.\|8.)\|python.*', ubuntu-latest)	1m 52s
ci (kubernetes, ./tests/bin/ci.sh -i 'test7.' -e 'test7(b.\|c.\|d.\|e.\|f.\|g.\|h.)', ubuntu-la...	13m 19s
ci (kubernetes, ./tests/bin/ci.sh -i 'test7(b.\|c.\|d.\|e.\|g.\|h.)', ubuntu-latest)	5m 19s
ci (kubernetes, ./tests/bin/ci.sh -i 'test7f.*', ubuntu-latest)	5m 16s
ci (kubernetes, ./tests/bin/ci.sh -i 'test8.*', ubuntu-latest)	2m 19s
ci (kubernetes, /tmp/lunchpail bat demos/data-prep-kit --concurrency 1 --auto-clean --target=$LUN...	13m 18s
ci (kubernetes, ./tests/bin/go.sh, ubuntu-latest)	1m 33s
ci (kubernetes, ./tests/bin/pipelines.sh, ubuntu-latest)	5m 9s
ci (local, ./tests/bin/ci.sh -e 'test(7.\|8.)\|python.*', ubuntu-latest)	33s
ci (local, ./tests/bin/ci.sh -i 'test7.' -e 'test7(b.\|c.\|d.\|e.\|f.\|g.\|h.)', ubuntu-latest)	2m 59s
ci (local, ./tests/bin/ci.sh -i 'test7(b.\|c.\|d.\|e.\|g.\|h.)', ubuntu-latest)	2m 1s
ci (local, ./tests/bin/ci.sh -i 'test7f.*', ubuntu-latest)	2m 13s
ci (local, ./tests/bin/ci.sh -i 'test8.*', ubuntu-latest)	37s
ci (local, /tmp/lunchpail bat demos/data-prep-kit --concurrency 1 --auto-clean --target=$LUNCHPAI...	13m 18s
ci (local, ./tests/bin/go.sh, ubuntu-latest)	1m 41s
ci (local, ./tests/bin/pipelines.sh, ubuntu-latest)	2m 13s
	1h 13m 40s

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