Use our own build/test image to build Istio

Currently we rely on upstream build/test image to run things like make build; or make test.

`make test` fails. It runs the test within the upstream image by default. Envoy fails on it, because upstream image is based on Ubuntu and our Envoy is built on centos.

Prow CI jobs works fine though, as they use our image instead of upstream's.

We should use our own image. For that we should take the same approach as upstream, i.e., have 2 different entrypoints, one for local usage, and one for prow.

Acceptance Criteria:

• `make build` and `make test` run without error using either `docker` (optional `podman`)