Remove LICENSE_MANAGEMENT_SETUP_CMD for license_scanning

The license_scanning job from the Security/License-Scanning.gitlab-ci.yml template does not require the LICENSE_MANAGEMENT_SETUP_CMD anymore. Some jobs have been failing with the latest scanner image due to the job defining this environment variable.

Per the documentation, we don't need to override this job. We can just let the scanner find the required tools on its own

If present, this variable will override the setup step necessary to install all the packages of your application (e.g.: for a project with a Gemfile, the setup step could be bundle install).