chore: don't use JENKINS_REPO for tags and publication

[lemeurherve]

This change removes the use of JENKINS_REPO used in tags generation and publication in profit of DOCKERHUB_REGISTRY/CONTAINER_ORGANISATION/CONTAINER_REPOSITORY so we can publish on other registries as well.

For that, it renames DOCKERHUB_ORGANISATION & DOCKERHUB_REPO to CONTAINER_ORGANISATION& CONTAINER_REPOSITORY and REGISTRY to DOCKERHUB_REGISTRY (more explicit), and replace the use of JENKINS_REPO with DOCKERHUB_ORGANISATION/DOCKERHUB_REPOSITORY in docker bake file, ./ci/publish.sh publication script, and HACKING.md documentation.

Preliminary pull request before the one allowing publication in multiple docker registries (only allowing, not actually publishing yet cf #1140 (comment))

Related:

• Also publish to GitHub container registry #1140

Testing done:

$ docker login
$ export CONTAINER_ORGANISATION=hlemeur

$ JENKINS_VERSION=2.528.3 ./.ci/publish.sh
Using the following settings:
* DOCKERHUB_REGISTRY: docker.io
* CONTAINER_ORGANISATION: hlemeur
* CONTAINER_REPOSITORY: jenkins
* JENKINS_VERSION: 2.528.3
* WAR_SHA: bfa31f1e3aacebb5bce3d5076c73df97bf0c0567eeb8d8738f54f6bac48abd74
* COMMIT_SHA: c5e4d807f8ec05a3f4c845e08869580877dcc570
* LATEST_WEEKLY: false
* LATEST_LTS: true
<snip>

$ docker inspect hlemeur/jenkins:2.528.3-lts
[
    {
        "Id": "sha256:1825aafdea6e58204b7eb323774c8c4e574318e0d18fb7bf27e0529abcb1b1ef",
        "RepoTags": [
            "hlemeur/jenkins:2.528.3",
            "hlemeur/jenkins:2.528.3-jdk21",
            "hlemeur/jenkins:2.528.3-lts",
            "hlemeur/jenkins:2.528.3-lts-jdk21",
            "hlemeur/jenkins:lts",
            "hlemeur/jenkins:lts-jdk21"
        ],
        "RepoDigests": [
            "hlemeur/jenkins@sha256:1825aafdea6e58204b7eb323774c8c4e574318e0d18fb7bf27e0529abcb1b1ef"
        ],
        "Comment": "buildkit.dockerfile.v0",
        "Created": "2026-01-11T13:48:33.84995609Z",
        "Config": {
            "User": "jenkins",
            "ExposedPorts": {
                "50000/tcp": {},
                "8080/tcp": {}
            },
            "Env": [
                "PATH=/opt/java/openjdk/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
                "LANG=C.UTF-8",
                "JENKINS_HOME=/var/jenkins_home",
                "JENKINS_SLAVE_AGENT_PORT=50000",
                "REF=/usr/share/jenkins/ref",
                "JENKINS_VERSION=2.528.3",
                "JENKINS_UC=https://updates.jenkins.io",
                "JENKINS_UC_EXPERIMENTAL=https://updates.jenkins.io/experimental",
                "JENKINS_INCREMENTALS_REPO_MIRROR=https://repo.jenkins-ci.org/incrementals",
                "COPY_REFERENCE_FILE_LOG=/var/jenkins_home/copy_reference_file.log",
                "JAVA_HOME=/opt/java/openjdk"
            ],
            "Entrypoint": [
                "/usr/bin/tini",
                "--",
                "/usr/local/bin/jenkins.sh"
            ],
            "Volumes": {
                "/var/jenkins_home": {}
            },
            "Labels": {
                "org.opencontainers.image.description": "The Jenkins Continuous Integration and Delivery server",
                "org.opencontainers.image.licenses": "MIT",
                "org.opencontainers.image.revision": "a0ab3fa020046a99ad7d9a49104cbaac4685e3b0",
                "org.opencontainers.image.source": "https://github.com/jenkinsci/docker",
                "org.opencontainers.image.title": "Official Jenkins Docker image",
                "org.opencontainers.image.url": "https://www.jenkins.io/",
                "org.opencontainers.image.vendor": "Jenkins project",
                "org.opencontainers.image.version": "2.528.3"
            }
        },
        "Architecture": "arm64",
        "Os": "linux",
        "Size": 288690242,
        "RootFS": {
            "Type": "layers",
            "Layers": [
                "sha256:4f9114eeb1e46da35d3a29b063ddfa69a0447888dd07117de77ddd565c54fb27",
                "sha256:4dccb090d7492f51e5752c94b2a4311cd1351cef18f05b5737f7138991e64906",
                "sha256:c2ff46607cfe9995b9e5310982ea95756ac9635f90b05db4c55415ef18dbeaf4",
                "sha256:38680db6fceda2720f91d241e9ffc1fe18bb5e80971d314de774ae8e05665e42",
                "sha256:cb337ba5f4bc7a25e13ee6f0e941f3c9ee55eae776e99c1105487c71c9f47748",
                "sha256:ec3cc3a9bb43919215cf5d39c940080aeaf993bb1a8e47a5ad28eff09eef3024",
                "sha256:b4d00230176fd3b195b4ac37dea53b8a3390decaa1238116d1c892f6320217de",
                "sha256:9dfb4b1bfc5bb8338db02c7d439500644c444502e27826aa3dd1bb578f758aa6",
                "sha256:5b5eb2fcc1a23df2a5a600d55f163ee5eea9fa2462385c7f8a6edc423add02c2",
                "sha256:9d6ca408160484d633fe9dede9a03e17f740a06a258db903a55520b122f4e679",
                "sha256:9a285ad710f7519f7868afd7bca59b59ba22e36627f9cfddebf61f343736d8c3",
                "sha256:3f83631eada5c1a69cb61ac5c9b3eef62f0bc9f61ddb39eec6e604fcb001d2ee"
            ]
        },
        "Metadata": {
            "LastTagTime": "2026-01-11T14:07:33.264826923Z"
        },
        "Descriptor": {
            "mediaType": "application/vnd.oci.image.index.v1+json",
            "digest": "sha256:1825aafdea6e58204b7eb323774c8c4e574318e0d18fb7bf27e0529abcb1b1ef",
            "size": 3117
        }
    }
]

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[timja]

I think these names would be better