DEVOPS-1391 Refactor server build workflow to use setup-docker-trust GitHub Action

[urbinaalex17]

Type of change

- [ ] Bug fix
- [ ] New feature development
- [X] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
- [ ] Build/deploy pipeline (DevOps)
- [ ] Other

Objective

We have standardized our setup of DCT in all other pipelines to use our custom bitwarden/gh-actions/setup-docker-trust action. We’d like to bring this standardization to the server build workflows.

Code changes

• build.yaml: Setup Docker Content Trust (DCT) step to use our GitHub Action bitwarden/gh-actions/setup-docker-trust@f955298c7a982b3fb5dbb73afd582c584fd5beec

Before you submit

• Please check for formatting errors (dotnet format --verify-no-changes) (required)
• If making database changes - make sure you also update Entity Framework queries and/or migrations
• Please add unit tests where it makes sense to do so (encouraged but not required)
• If this change requires a documentation update - notify the documentation team
• If this change has particular deployment requirements - notify the DevOps team