feat(staging): 25.12 genetics staging data update

[project-defiant]

Context

This PR adds the configuration changes to the gentropy staging dags used to generate 25.12 release data.

It also unifies the way to build orchestration images. The updated logic is in the artifact.yaml file that corresponds to the github action responsible for building and pushing the orchestration related Docker images.

Implementations

The PR includes:

1. Change in how the artifact.yaml is triggered - now only manually.
2. If artifact.yaml is triggered from the branch, no image is build, if it is triggered from tag, then images are build and pushed to the registry - this ensures no overwrites (branch name is not used as image tag).
3. Push images to GAR on open-targets-genetics-dev project via OIDC, not using long lifetime service account anymore.
4. Push images to GitHub container registry
5. Build attestations and include in GAR
6. Short docs about images.
7. Adds new harmonisation and fine-mapping config changes for 25.12 release

The most important change is that now we build both images:

• gentropy overwrite image used for running gwas catalog harmonisation batch job
• orchestration service image
  and include them into the GitHub Container Registry for public usage.

Action was tested on v25.12-staging.5 which produced artifacts for the repository and GAR.