Enable K8-only secret management and remove secrets from Github workflows/Dockerfile(s)

[ericdrosas87]

User story

As the cloud-ops engineer of the EDC, I need to remove the build arg secrets within the Github workflows and project Dockerfile(s), and update the secret from which the client build is dependent so as to eliminate the need for the frontend developers to manage secrets in the repo.

Definition of done

I've removed the need for build arg secrets in the Github workflows and Dockerfile(s)

[ericdrosas87]

Starting work on this now @blnkt , if all goes will I'll make the same change to investigations-client

[ericdrosas87]

Starting work on this now @blnkt , if all goes will I'll make the same change to investigations-client

Actually ignore this comment @blnkt - I keep forgetting the Investigations API and client aren't running on K8 as of yet