Automate Updating ClamAV Image

One of two MRs needed to fix #264

Changes clamav-run.sh to download the definitions stored as a job artifact of av-updater's build stage. Verifies expected files and prints the definitions version. This now runs on the registry1 clamav image instead of the manually maintained image in IB tools.

Successful pipeline run here: https://repo1.dso.mil/dsop/opensource/pipeline-test-project/ubi8/-/jobs/2665369

The other MR av-updater!2 (merged) (merged) must be merged in order to test the current code because the curl command has been changed to point to the master branch.