fix: updates e2e tests checkout ref during image publishing

[jpower432]

Description

When rebuilding old images, we need to run the E2E from that references to avoid issues with breaking changes in the CLI. This solution checks out the git repository at the references determined by the trigger and uses the Docker build-push action with a path context.

Fixes #332

Type of change

• Bug fix (non-breaking change which fixes an issue)

How has this been tested?

• https://github.com/RedHatProductSecurity/trestle-bot/actions/runs/10600722915
• Local testing and inspection of image produced

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[gvauter]

LGTM