Get (Jenkins) pipeline artifacts for external use served from S3 (not Jenkins)

[kltm]

Currently, there are some Jenkins jobs that produce artifacts that are used by external pipelines that are being served from Jenkins. Jenkins is not a file server, the LBL network is not perfect, and Jenkins often has a funny idea about "last successful". As much as possible, unless there is a very good reason, artifacts for external use should be served from our CDN in AWS S3, e.g. http://build-artifacts.berkeleybop.org/job-foo/latest/blah.bar.

The current examples for this are:

• [x] https://build.berkeleybop.org/job/export-lego-to-legacy/ used by MGI to pick up their Noctua models to feed back into their own pipeline

@cmungall @ukemi @balhoff.

[kltm]

The job has been updated to push to the CDN. For example:

http://build-artifacts.berkeleybop.org/export-lego-to-legacy/latest/gpad/mgi.gpad http://build-artifacts.berkeleybop.org/export-lego-to-legacy/latest/gpad/production/mgi.gpad

For now, these should be the URLs used by external resources to pick up their files from the BBOP pipeline. @ukemi

[kltm]

Note relation to #265 .