Retain generated corpus and pretranslation files for a build

[ddaspit]

Currently, Serval deletes corpus and pretranslation files once a build has finished. This makes it difficult to debug issues and to perform testing. Instead, Serval should retain the files after a build has finished. The files should be deleted after a predetermined amount of time (maybe 30 days).

[ddaspit]

This is needed to support gray box testing by the test team.

[johnml1135]

Do we want this for QA only? Do we want this controllable by a flag?

[ddaspit]

I think it would be good to do this on production as well, since it will be helpful for debugging.

[ddaspit]

We still need to implement a method for cleaning up the files.

[Enkidu93]

I know you were asking about an approach in the PR above, @ddaspit: I'm thinking I'll just add a DateFinished to the machine build model which we can set in BuildJobService.BuildJobFinishedAsync and then add another RecurrentTask similar to the ModelCleanupService to delete the build artifacts after a certain amount of time (is 30 days long enough?). Does that sound like a good approach? We could wait until 30 days after the code has been pushed to production and then push another change to delete build artifacts for translation engines which don't have a DateFinished property set to avoid indefinitely storing the build artifacts from builds build recently or we could set the existing builds to have the current date at the time of the push (probable simpler).

[johnml1135]

The longest that I could imagine that a job could take would be 1 day. If we set the expiration for 30 days and key off of DateCreated (or whatever the field is), I think it could be simpler to implement and not have an old vs. new data issue.