testing/helm: fix displayed version
Current behavior:
$ helm version
version.BuildInfo{Version:"v3.9+unreleased", GitCommit:"8949419005bbc0913577b96f5d3583352ca1c694", GitTreeState:"clean", GoVersion:"go1.18.2"}
With this commit:
$ helm version
version.BuildInfo{Version:"3.9.0", GitCommit:"", GitTreeState:"", GoVersion:"go1.18.2"}
The GitCommit and GitTreeState are taken from the HEAD of our aports
repo when the build happens, which doesn't make any senses so I think we should leave them blank.
Also remove prepare() since upstream already uses procfs
version 0.7.3 - https://github.com/helm/helm/blob/823d92942119dfa07fd763bf6306bd67686811a8/go.mod#L134