cleanup: remove pre-test build steps (create egg-info dir, create static entry_points.txt file)

Tests seem to run fine locally during a package build without these; egg-info directory creation should be handled by pybuild, and entry_points are declared in the pyproject.toml file.

Should also marginally improve reproducibility, since the escaped newline may be interpreted differently by different shells (bash vs sh for example).

cc @jspricke