fix(build): Do not remove README_STARTUP file required by IPython.

[vegano1]

To save space on the OT-2 builds we remove tests and readme files in the post-build step which is great, unfortunately, IPython does not work without its 'README_STARTUP' file which we also removed. So Lets exclude this file when cleaning up.

Closes: RQA-2412

Test plan

• [x] Create an OT-2 build and make sure we can run Jupyter Notebook and run protocols

Log Changes

• Exclude the README_STARTUP file when cleaning out tests and readme files