Another CI runs that saw this failure:

https://openshift-gce-devel.appspot.com/build/origin-ci-test/logs/release-openshift-origin-installer-e2e-aws-upgrade-4.0/928
https://openshift-gce-devel.appspot.com/build/origin-ci-test/logs/release-openshift-origin-installer-e2e-aws-upgrade-4.0/927
https://openshift-gce-devel.appspot.com/build/origin-ci-test/logs/release-openshift-origin-installer-e2e-aws-upgrade-4.0/926

Same error example:
curl https://storage.googleapis.com/origin-ci-test/logs/release-openshift-origin-installer-e2e-aws-upgrade-4.0/928/artifacts/e2e-aws-upgrade/clusteroperators.json | jq '.items[] | select(.status.conditions[] | .type == "Available" and .status != "True") | [.metadata.name, .status.conditions]'
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 61288  100 61288    0     0   123k      0 --:--:-- --:--:-- --:--:--  123k
[
  "openshift-apiserver",
  [
    {
      "lastTransitionTime": "2019-04-04T20:43:13Z",
      "reason": "AsExpected",
      "status": "False",
      "type": "Failing"
    },
    {
      "lastTransitionTime": "2019-04-04T20:43:13Z",
      "reason": "AsExpected",
      "status": "False",
      "type": "Progressing"
    },
    {
      "lastTransitionTime": "2019-04-04T21:01:33Z",
      "message": "Available: v1.quota.openshift.io is not ready: 503",
      "reason": "Available",
      "status": "False",
      "type": "Available"
    },
    {
      "lastTransitionTime": "2019-04-04T20:43:13Z",
      "reason": "AsExpected",
      "status": "True",
      "type": "Upgradeable"
    }
  ]
]

This is kind of known. I suspect https://github.com/openshift/cluster-config-operator/pull/25 started this.
I need to merge https://github.com/openshift/origin/pull/22425 and this failure should go away.

In fresh env of latest payload 4.0.0-0.nightly-2019-04-05-165550, also see: 
oc get co 
... 
openshift-apiserver                  4.0.0-0.nightly-2019-04-05-165550   False ... 
... 
 
oc get co openshift-apiserver -o yaml 
... 
status: 
  conditions: 
  - lastTransitionTime: 2019-04-08T02:41:44Z 
    reason: AsExpected 
    status: "False" 
    type: Failing 
  - lastTransitionTime: 2019-04-08T02:41:00Z 
    reason: AsExpected 
    status: "False" 
    type: Progressing 
  - lastTransitionTime: 2019-04-08T03:11:03Z 
    message: 'Available: v1.quota.openshift.io is not ready: 503' 
    reason: Available 
    status: "False" 
    type: Available 
... 
 
oc get openshiftapiserver -o yaml 
... 
  status: 
    conditions: 
    - lastTransitionTime: 2019-04-08T02:32:47Z 
      reason: NoUnsupportedConfigOverrides 
      status: "True" 
      type: UnsupportedConfigOverridesUpgradeable 
    - lastTransitionTime: 2019-04-08T02:32:48Z 
      status: "False" 
      type: ConfigObservationFailing 
    - lastTransitionTime: 2019-04-08T02:36:32Z 
      status: "False" 
      type: ResourceSyncControllerFailing 
    - lastTransitionTime: 2019-04-08T03:26:32Z 
      message: 'v1.quota.openshift.io is not ready: 503' 
      status: "False" 
      type: Available 
...

Continuing comment 3:
$ watch oc get clusteroperator/openshift-apiserver
openshift-apiserver   4.0.0-0.nightly-2019-04-05-165550   False       False         False     0s
...
openshift-apiserver   4.0.0-0.nightly-2019-04-05-165550   True       False         False     0s

openshift-apiserver is always flapping between True and False

*** This bug has been marked as a duplicate of bug 1694226 ***