Automatic merge from submit-queue (batch tested with PRs 41287, 41636, 44881, 44826)

Bump to go1.8 and remove the edge GOROOT

**What this PR does / why we need it**:

Bumps to go1.8; we get:
 - performance improvements
 - build time improvements
 - the possibility to remove the hacky edge-GOROOT for arm and ppc64le that must use go1.8
 - all other awesome features that are included in go1.8: https://golang.org/doc/go1.8

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes https://github.com/kubernetes/kubernetes/issues/38228

**Special notes for your reviewer**:

@ixdy Please push the image ASAP so we can see if this passes all tests

**Release note**:

```release-note
Upgrade go version to v1.8
```
cc @ixdy @bradfitz @jessfraz @wojtek-t @timothysc @spxtr @thockin @smarterclayton @bprashanth @gmarek