Using "--no-cache-dir" flag in pip install ,make sure dowloaded packages
by pip don't cached on system . This is a best practise which make sure
to fetch ftom repo instead of using local cached one . Further , in case
of Docker Containers , by restricing 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
This has adapted for use with bazel from the original commit
a26e93769ebefd82593a43e22fb13a09717cfa6d.
In particular, the style has been made consistent with internal python style
guidelines, and the packages (including the main entrypoint) have been
refactored in order to allow bazel testing targets.
PiperOrigin-RevId: 283484433