ci: Bump test deployment workflow to version 2

[slothkong]

Hello @slanglois,

During our chat on Wednesday, we promised we would open PRs for ECWMF-devloped Items to enable catalog-centric test automation. This is one of such PRs.

What's new

• Updated version of the GitHub Action: This new v2 version has workflow_dispatch.input values compatible with the orchestrator workflows that we will be releasing as part of Test deployment via orchestrated GitHub Actions ewc-community-hub#58

• EUMETSAT site credentials: For the time being, we have filled in all necessary GitHub action secrets with credentials belonging to the internal-eumetsat-sandbox tenancy as target environment for test (you had used this tenancy in the past, during an EWC workshop).

• Conservative defaults: Purposely removed defaults for inputSpecJson and pathToRequirementsFile. This is to avoid situations in which the upstream orchestrator ommits this values (because they are not needed), but then the children workflows in this repo override those unset values, with unexpected results.

UPDATE: We are still pending on a documentation page for SOPs about credentials sharing and rotation. But for now, you can simply let us know which GH repo you would like to make test-enabled, and we will set them on it for you.

cc: @xavierabellan

[slothkong]

@slanglois , if this clear, please squash-merge and delete the branch right after 😇 🙏