Add test script with data and verify that implemented feature works

Test script contains function `remove_attribute` which can be
placed in cclutils package to provide wrapper for this new
functionality.

Test script has been implemented, but it is not automated (CI/CD).
It was not automated because it looks like corpus2 tests are not
maintained (not included in CI/CD and make test informs about
failed tests) so not sure where new tests should be "attached".