ci: Rubocop job fails when we only change the `.rubocop_todo` folder
Problem
This job failed with the following error:
/usr/bin/bash: line 285: rspec/changed_files.txt: No such file or directory
The problem seems to come from https://gitlab.com/gitlab-org/gitlab/-/blob/0e55d8ac5b82f9eea1943f4eec7ef6f8de84cc1b/.gitlab/ci/static-analysis.gitlab-ci.yml#L118:
# RSPEC_CHANGED_FILES_PATH=rspec/changed_files.txt
select_existing_files < "${RSPEC_CHANGED_FILES_PATH}" > "${RUBOCOP_TARGET_FILES}"