chore: use `--no-cache-dir` flag to `pip` in dockerfiles, to save space

[rajpratik71]

using "--no-cache-dir" flag in pip install ,make sure downloaded packages by pip don't cached on system . This is a best practice which make sure to fetch from repo instead of using local cached one . Further , in case of Docker Containers , by restricting caching , we can reduce image size. In term of stats , it depends upon the number of python packages multiplied by their respective size . e.g for heavy packages with a lot of dependencies it reduce a lot by don't caching pip packages.

Further , more detail information can be found at

https://medium.com/sciforce/strategies-of-docker-images-optimization-2ca9cc5719b6

Signed-off-by: Pratik Raj [email protected]

[ericwill]

Hi @Rajpratik71, this repo is no longer used in Che, instead we have moved all the relevant sidecar images to the che-dockerfiles org. Perhaps it would be best to open your PR's there?