Clean up any remaining processing worker versions

A few dozen worker versions in all of our instances still had a processing state. They were unusable before anyway, but now they cause crashes: ARKINDEX-BACKEND-2AW.

I cleaned everything up manually in a shell, but this migration at least automates the cleanup for everyone else.

changed milestone to %Arkindex 1.6.6

requested review from @babadie

assigned to @erouchet

added 3 commits

• 6c645ed7...10ca409a - 2 commits from branch release-1.6.6
• 7aaa889a - Clean up any remaining processing worker versions

Compare with previous version

enabled an automatic merge when all merge checks for 7aaa889a pass

merged