Rename 'sast_container' to 'container_scanning' in GITLAB_FEATURES variable

In the GITLAB_FEATURES environment variable exposed to jobs, there is a feature named sast_container. It should be named container_scanning instead.

  • Add container_scanning value to GITLAB_FEATURES variable
  • Update documentation to deprecate the sast_container value
  • Add a deprecation note in the 11.5 blog post
Edited by Fabio Busatto