remove conformance image test for 1.15

These is an against an old enough codebase to be irrelevant for
the upstream community.

Signed-off-by: Tim Pepper <tpepper@vmware.com>

config/jobs/kubernetes/sig-testing/conformance-e2e.yaml

@@ -144,47 +144,6 @@ periodics:
     description: Runs conformance tests using image against latest kubernetes master with a kubernetes-in-docker cluster
     testgrid-alert-email: davanum@gmail.com
     testgrid-num-columns-recent: '3'
-- interval: 3h
-  name: ci-kubernetes-conformance-image-1-15-test
-  labels:
-    preset-service-account: "true"
-    preset-bazel-scratch-dir: "true"
-    preset-bazel-remote-cache-enabled: "true"
-    preset-dind-enabled: "true"
-    preset-kind-volume-mounts: "true"
-  spec:
-    containers:
-    - image: gcr.io/k8s-testimages/kubekins-e2e:v20200623-2424179-1.15
-      args:
-      - "--job=$(JOB_NAME)"
-      - "--root=/go/src"
-      - "--repo=k8s.io/test-infra=master"
-      - "--repo=k8s.io/kubernetes=release-1.15"
-      - "--service-account=/etc/service-account/service-account.json"
-      - "--upload=gs://kubernetes-jenkins/logs"
-      - "--scenario=execute"
-      - "--"
-      # the script must run from kubernetes, but we're checking out kind
-      - "bash"
-      - "--"
-      - "-c"
-      - "cd ./../../k8s.io/kubernetes && source ./../test-infra/experiment/kind-conformance-image-e2e.sh"
-      # we need privileged mode in order to do docker in docker
-      securityContext:
-        privileged: true
-      resources:
-        requests:
-          # these are both a bit below peak usage during build
-          # this is mostly for building kubernetes
-          memory: "9000Mi"
-          # during the tests more like 3-20m is used
-          cpu: 2000m
-  annotations:
-    testgrid-dashboards: conformance-all, conformance-kind, sig-testing-kind
-    testgrid-tab-name: conformance-image, 1.15 (dev)
-    description: Runs conformance tests using image against kubernetes 1.15 branch with a kubernetes-in-docker cluster
-    testgrid-alert-email: davanum@gmail.com
-    testgrid-num-columns-recent: '3'
 
 - name: ci-kubernetes-conformance-kind-ga-only
   cluster: k8s-infra-prow-build