Enable host DNS resolution in virtualbox driver by default

[clocklear]

Addresses #3451; as such, there is more context over there.

The default settings for the VirtualBox machine enables DNSProxy and disables HostDNSResolver. I'd like to propose reversing these settings. If the host is used for DNS resolution, we can enable the kubernetes cluster to resolve registry URLs like registry.kube-system.svc.cluster.local:80, assuming that the host has properly configured a cluster.local resolver that routes traffic to the minikube network.

This should not cause any backwards-incompatible issues (so far as I can tell) and should be a drop-in replacement for what folks are already using. I am, of course, open to putting this behind some sort of runtime configuration flag.

[minikube-bot]

Can one of the admins verify this patch?

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: clocklear
To fully approve this pull request, please assign additional approvers.
We suggest the following additional approver: balopat

If they are not already assigned, you can assign the PR to them by writing /assign @balopat in a comment when ready.

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[clocklear]

/assign @balopat

[clocklear]

This Travis failure seems unrelated to my PR.

[clocklear]

@balopat do you mind taking a look a this?

[tstromberg]

@minikube-bot OK to test

[clocklear]

Thanks @tstromberg; these failures don't look related to my PR, can you confirm?

[balopat]

LGTM, thank you!

[balopat]

I'm puzzled by the travis issue, I restarted it and it passed.
Integration tests do seem like unrelated flakes:
VirtualBox: #2749
KVM: I haven't seen this one before but it can't be due to this change:

    --- FAIL: TestStartStop/start_stop_with_containerd_runtime (203.25s)
    	util.go:78: Error running command: stop . Output: Stopping local Kubernetes cluster...
    		Error stopping machine:  Error stopping host: minikube: Could not stop VM, current state Running

[clocklear]

Thanks guys!

[chancez]

I'm pretty certain, while this is actually something I personally want, it seems to be causing breakage for me. It doesn't seem to even be using my host's DNS settings either.

I can say for certain, I was previously able to query some hosts fine, but now it's failing. I run my own DNS server on my network as well, and on 0.32 I don't even see the queries in the logs. After going to 0.31, it seems to be actually using my host's DNS again, since the queries in minikube do show up on my DNS servers logs.