Delete README generator script

1. It is currently not used by any CI workflow

2. It is out of sync with build-definitions

3. Syncing it to the build-definitions variant may cause problems. The
   build-definitions variant handles README generation a bit differently
   and requires the existing READMEs to be in a specific format. All the
   READMEs in build-definitions were updated to follow that format, but
   the same cannot be said for the tasks that have already moved out of
   build-definitions.

Signed-off-by: Adam Cmiel <[email protected]>

Author: chmeliik