v0.3 backport: Add Java coverage reporting

[ches]

What this PR does / why we need it:

Backports #686 to v0.3-branch. Also backports #410, which was a final missing piece for v0.3 after #407—this fixes the Prow job for publish-docker-images on the branch.

I have possibly a few of these housekeeping-ish things that I want to bring in internally, and as much as possible / whenever valuable for mainline Feast I'm trying to do things as upstream master => upstream backport => bring backport in-house. If PR reviews and so forth become a burden though, if you aren't supporting any v0.3 deployments yourselves anymore, I'm happy for us to "formally" take ownership of the maintenance branch in whatever ways make sense.

Does this PR introduce a user-facing change?:

NONE

[ches]

/assign @woop

[ches]

/hold

I think some of the work for setting Feast version consistently needs to be backported also to fix the publish-docker-images Prow step, I'll look at this.

[woop]

Thanks @ches

I'm happy for us to "formally" take ownership of the maintenance branch in whatever ways make sense.

Given the maturity of the project and intention of most "regulars" of the project, I think we will have less problems with people cleaning things up than they introduce. Happy to reduce red tape. Also happy for you to formally take ownership of 0.3 that makes things easier.

Please let me know if there are any technical challenges (access?) that stand in your way. I have made you an admin on the repo if that helps with anything.

[ches]

Please let me know if there are any technical challenges (access?) that stand in your way. I have made you an admin on the repo if that helps with anything.

None that I'm currently aware of, I'll try the next release process after we get a few things in and see if anything comes up.

We're probably the only ones opening PRs against v0.3-branch, I can ask another Agodan to be a reviewer for these. I guess at least one of us would need to be an approver for Prow to do the merges without asking one of you.

[woop]

Please let me know if there are any technical challenges (access?) that stand in your way. I have made you an admin on the repo if that helps with anything.

None that I'm currently aware of, I'll try the next release process after we get a few things in and see if anything comes up.

We're probably the only ones opening PRs against v0.3-branch, I can ask another Agodan to be a reviewer for these. I guess at least one of us would need to be an approver for Prow to do the merges without asking one of you.

Feel free to add more contributors/reviewers/approvers as needed.

[ches]

/hold cancel

[woop]

/lgtm

[woop]

/approve

[feast-ci-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ches, woop

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[ches]

Thanks for the quick reviews!