Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

test image for a release 1.7 based sample-apiserver

**What this PR does / why we need it**:
In our e2e test suite we have use an image "gcr.io/kubernetes-e2e-test-images:k8s-aggregator-sample-apiserver:1.7v2". We need a way to build a fresh image that can we can use instead of that one. Especially we need one that has a multi-arch fat manifest so e2e tests can be run across multiple architectures.

This is especially important since we are in the process of promoting the test in question to the conformance suite - https://github.com/kubernetes/kubernetes/pull/63947

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:
/cc @mkumatag 
/cc @ixdy 
/cc @luxas 

**Release note**:

```release-note
NONE
```