Remove krel patch-announce

[saschagrunert]

What type of PR is this?

/kind deprecation
/kind cleanup

What this PR does / why we need it:

As discussed in the Release Engineering Meeting, we now remove krel patch-announce in favor of the more general krel announce subcommand.
Further refactorings will target the pkg/patch package, where some of
its components will be re-used by other tools.

Which issue(s) this PR fixes:

Fixes #1312

Special notes for your reviewer:

None

Does this PR introduce a user-facing change?

- Removed `krel patch-announce` in favor of the more general `krel announce` subcommand

[k8s-ci-robot]

@saschagrunert: Adding label: do-not-merge/blocked-paths because PR changes a protected file.

Reasons for blocking this PR:

[Changes to certain release tools can affect our ability to test, build, and release Kubernetes. This PR must be explicitly approved by SIG Release repo admins.]

• gcb/patch-announce/cloudbuild.yaml

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[justaugustus]

@saschagrunert -- We should support the replacement before deprecating this.
/hold

[saschagrunert]

@saschagrunert -- We should support the replacement before deprecating this.
/hold

Working on handbook updates here now: https://github.com/kubernetes/sig-release/pull/1098/files

[justaugustus]

@saschagrunert -- More explicitly, before we remove patch-announce, are we positive that announce has feature parity?

[saschagrunert]

@saschagrunert -- More explicitly, before we remove patch-announce, are we positive that announce has feature parity?

Alright, those are the things patch-announce did:

1. Creating an announcement mail header
2. Building the release notes via ./relnotes
3. Formatting the notes as HTML and merging it with the header
4. Sending the announcement

Whereas announce only does:

1. Downloading the announcement from the Google Cloud Bucket (previously built by anago)
2. Sending the announcement

Building the release notes again just for the mail should not be necessary, because krel changelog already does this job (anago expects a generated HTML after the notes have been built).

To streamline the overall process, I suggest to reuse parts of pkg/patch (not removed in this PR) for the golang based anago to create the announcement on the bucket.

It should be safe to remove krel patch-announce since it is not used in production, yet.

[justaugustus]

SGTM!
/hold cancel
/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: justaugustus, saschagrunert

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