Automatic merge from submit-queue

Add flag to node e2e test specifying location of ssh privkey

**What this PR does / why we need it**: in CI, the ssh private key is not always located at `$HOME/.ssh`, so it's helpful to be able to override it.

@krzyzacy here's my resurrected change. I'm not sure why I neglected to follow-through on it originally.

**Release note**:

```release-note
NONE
```