Update clair-local-scan in Container Scanning

Follow-up of https://gitlab.com/gitlab-org/gitlab-ee/issues/10241:

The Docker images in Container Scanning, especially arminc/clair-local-scan:v2.0.6, cause a bug when used with an XFS base file system. To avoid this bug, the images must be built with docker >= 18.09.03. Only the latest versions are therefore compatible. We must upgrade to v2.0.8 (the tag format changed since, and now contains the commit sha: v2.0.8_fe9b059d930314b54c78f75afe265955faf4fdc1).

It should be done during the RM rotation, but to ease the follow-up with this customer, I'm creating this issue.