Actually make the pushed version directory match binary versions

A small bug from #11941: When we push to GCS, we were pushing bucket
names that matched the old pattern `git describe`, e.g.:

gs://kubernetes-release/ci/v1.1.0-alpha.0-2413-g986d37d/

But after #11941, the binaries inside these actually have versions that look like:

v1.1.0-alpha.0.2413+g986d37d

to more closely match up with semver.

This pull makes the GCS directory match the binaries it's already serving.