Rearchitect Build to Use Normal Containers in a Pod vs. Init Containers

[aaron-prindle]

This is a feature request to have Build use "normal" Pod containers for Step execution instead of the current implementation which uses init containers.

Reasoning

• Currently getting logs of Build steps can be tricky as init container logs are garbage collected much more aggressively. This change would allow for the Build Step logs to be in "normal" Pod containers
• Allows for sidecar containers to be used in conjunction with Builds
• • Istio sidecars
• • Log uploading

Potential Issues

Build will no longer support sets of Steps that would rely on newly built images from a previous step (as all images are pulled in initialization). This use case can be supported in a https://github.com/knative/build-pipeline though.

Investigation of Alternatives (in the context of allowing sidecars for knative/build)

https://docs.google.com/document/d/1vADt9yl21jOS085ZGjuNTJFjQegE6CniGFdlEJdyCrw/edit#heading=h.c0uts5ftkk58