Prepare ci.mariadb.org as storage for connectors artifacts

ci.mariadb.org is used for both:

• storing intermediate artifacts used in the build chain
• storing release artifacts that will be published on the official mirrors

The directory tree should satisfy the following conditions:

• should be easy enough to identify and download the artifacts for a given commit
• should keep the artifacts stored for a reasonable amount of time, for each commit

Inspired by the server CI layout, there will be:

• a separate connectors path, i.e. ci.mariadb.org/connectors with each categ. ODBC,C,CPP
• the entry-point, the tarball-docker builder will create dirs under each categ. named after its build-number.
• each build-number represents a unique change that was built in Buildbot
• each build triggered by the tarball-docker builder will publish its artifacts under the build-number dir tree

For a given change i.e. commit, one will start from the tarball-docker build-number
and then construct the path to the artifacts on ci.mariadb.org

The tree will look like this:

└── connectors

    ├── c

    │   ├── 1

    │   │   ├── cc-amd64-debian12

    │   │   │   ├── cc_bintar.tar.gz

    │   │   │   └── cc_deb.deb

    │   │   └── c.tar.gz

    │   └── 2

    ├── cc

    │   ├── 1

    │   └── 2

    │       ├── ccpp-amd64-rhel9

    │       │   ├── ccpp_bintar.tar.gz

    │       │   └── ccpp_rpm.rpm

    │       └── cpp.tar.gz

    └── odbc

        ├── 1

        │   ├── odbc-amd64-rhel10

        │   │   ├── odbc_bintar.tar.gz

        │   │   └── odbc_rpm.rpm

        │   └── odbc.tar.gz

        └── 2

Required changes:

• dir Initialization under the buildbot master hosts (Ansible)
• location definitions for nginx CI template (buildbot repo)
• ensure package rotation works i.e. bb_packages_rotation script update (if needed)
• autofs configuration on the dedicated connector infra faust