Run upload-docker-image on release

When we tag a release of Zuul, run the upload-docker-image job, but
tell it to do so in a non-promote mode.  This will cause it to
directly upload the images to Docker Hub with the final tags applied.
We want to do this in the release pipeline so that we get images
built with the correct version number based on the git tag.

When run in a pipeline with a tag attribute set, this will use all
three lengths of the version number (3.19.0, 3.19, 3) as tags instead
of the single 'latest' tag which is what is applied in the promote
pipeline.

This temporarily comments out the other release jobs so that we can
manually enqueue the most recent tag and retroactively build and
publish it to Docker Hub.  Once this works, we will re-enable those
two jobs.

Change-Id: If3bdbe4fac7e8ebf8b2bb087b578df7f860cbea4
Depends-On: https://review.opendev.org/734890

.zuul.yaml

@@ -139,21 +139,30 @@
         - context: .
           repository: zuul/zuul
           target: zuul
+          tags:
+            # If zuul.tag is defined: [ '3', '3.19', '3.19.0' ].  Only works for 3-component tags.
+            # Otherwise: ['latest']
+            &imagetag "{{ zuul.tag is defined | ternary([zuul.get('tag', '').split('.')[0], '.'.join(zuul.get('tag', '').split('.')[:2]), zuul.get('tag', '')], ['latest']) }}"
         - context: .
           repository: zuul/zuul-executor
           target: zuul-executor
+          tags: *imagetag
         - context: .
           repository: zuul/zuul-fingergw
           target: zuul-fingergw
+          tags: *imagetag
         - context: .
           repository: zuul/zuul-merger
           target: zuul-merger
+          tags: *imagetag
         - context: .
           repository: zuul/zuul-scheduler
           target: zuul-scheduler
+          tags: *imagetag
         - context: .
           repository: zuul/zuul-web
           target: zuul-web
+          tags: *imagetag
 
 - job:
     name: zuul-upload-image
@@ -311,5 +320,13 @@
               download_artifact_job: zuul-build-dashboard
     release:
       jobs:
-        - zuul-release-python
-        - zuul-publish-tox-docs
+        # - zuul-release-python
+        # - zuul-publish-tox-docs
+        - upload-docker-image:
+            secrets:
+              name: docker_credentials
+              secret: zuul-dockerhub
+              pass-to-parent: true
+            vars:
+              <<: *zuul_image_vars
+              upload_docker_image_promote: false