Bugfix: Dockerfile RUN cache

[carlomion]

Following the introduction of the Dockerfile RUN cache in #554 , the build has started failing, likely due to concurrent access to the same cached folder during the multi-architecture build process: https://github.com/mediagis/nominatim-docker/actions/runs/8722047757

This PR does the following:

• avoid sharing of the cache
• uses the docker/metadata-action@v5 to define the Docker label and tag for the image
• the docker build is always done in the CI pipeline, so that the arm64 build is also built, but only pushed to Dockerhub if on the master branch

[what-the-diff]

PR Summary

• Enhanced Workflow for Docker Image Creation and Versioning
  An improvement to the system handling Docker image creation (a kind of "blueprint" for creating a program) in the continuous integration workflow file (.github/workflows/ci.yml). This update includes a new step to calculate Docker tags and labels, which helps to properly version and categorize each image.

• Simplified Docker Tag Process
  The old method of setting the Docker image's date tag has now been removed, making the overall process more efficient and less error-prone.

• Updated Docker Build and Push method
  The process of building (creating from the blueprint) and pushing (sending to a repository where it can be shared with others) the Docker image has been greatly improved. It now uses a trusted and efficient third-party software (docker/build-push-action@v5).

• Optimized Docker Build Commands and Cache Incorporation
  Changes have been made to the commands that build the Docker image in the file 4.4/Dockerfile. These commands now feature improved caching. Caching accelerates the build process by reusing previously stored or calculated information rather than recalling or recalculating it.

• Streamlined Docker Image with Package Removal
  Several packages, which can be viewed as sets of functionalities, were removed from the file 4.4/Dockerfile. This helps to trim down the Docker image size, increasing its efficiency and reducing the storage space it requires.

• Improved Docker Image Cleanup
  The way cleaning up after building the Docker image works has been revised, making it more effective and efficient.

[leonardehrenfried]

Again, this is a really nice PR. Lets see if the build succeeds this time.

[leonardehrenfried]

I'm a bit confused why concurrent access was even possible. I was under the impression that these are two totally different machines/vms and don't share anything, let alone disk. Where is this cache being saved to?

[carlomion]

As explained here https://docs.docker.com/reference/dockerfile/#run---mounttypecache by default the parameter RUN --cache sharing is shared, meaning that the arm64 and amd64 builds, running in parallel inside the same GitHub runner (here is a quick overview of the multi-platform build done by Docker) will conflict with each other.