Add cleanup of python artifacts (NVIDIA#10355)

This PR removes `__pycache__`, `.so` & `.pyc` files.

Authors:
  - GALI PREM SAGAR (https://github.com/galipremsagar)

Approvers:
  - Vyas Ramasubramani (https://github.com/vyasr)

URL: rapidsai/cudf#10355

build.sh

@@ -168,6 +168,10 @@ if hasArg clean; then
         rmdir ${bd} || true
     fi
     done
+
+    # Cleaning up python artifacts
+    find ${REPODIR}/python/ | grep -E "(__pycache__|\.pyc|\.pyo|\.so$)"  | xargs rm -rf
+
 fi