[Proxy] Split domain name

[numerology]

Get a dedicated subdomain name
Test endpoint is working at https://3b55c042b138bf86-dot-us-central2.pipelines.googleusercontent.com/#/pipelines

The new config is at https://storage.googleapis.com/ml-pipeline/proxy-agent-config.json

---

This change is 

[numerology]

/assign @IronPan

Do you have any good advise in where to put the config file? I think the best practice is to factor out the 'greatest common divisor' but currently I made a separate copy.

[IronPan]

Is it possible in the original config file to have

"agent-docker-containers": {
    "latest": {...}
    "pipelines": {...}
}

[numerology]

Is it possible in the original config file to have

"agent-docker-containers": {
    "latest": {...}
    "pipelines": {...}
}

Good call. We will need to request datalab team to do that

[rmgogogo]

Thanks Jiaxiao.

/lgtm

[IronPan]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: IronPan

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:

• proxy/OWNERS [IronPan]

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

[numerology]

/retest

[numerology]

/retest