e2e: fix restarting the apiserver

[yujuhong]

The string used to match the image name of the apiserver (e.g., gcr.io/google_containers/kube-apiserver:3be...),
but this no longer works. Change the test to locate the kube-apiserver container by name.

[yujuhong]

This fixes #42680

[k8s-reviewable]

This change is 

[dchen1107]

/lgtm

and

/approve

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is APPROVED

The following people have approved this PR: dchen1107, yujuhong

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[yujuhong]

@dchen1107, to be clear:

<=1.5:

$ sudo docker ps
CONTAINER ID        IMAGE                                      COMMAND                  CREATED             STATUS              PORTS               NAMES
b94faa1cd7c8        gcr.io/google_containers/kube-apiserver:3be8582ae567bd905ed21ca8b431375d            "/bin/sh -c '/usr/loc"   3 months ago        Up 3 months                             k8s_kube-apiserver.3878919f_kube-apiserver-jenkins-e2e-master_kube-system_d33de50a79071a0944b2e846f71fbebc_184307b4

Now:

$ sudo docker ps
CONTAINER ID        IMAGE                                      COMMAND                  CREATED             STATUS              PORTS               NAMES
bcd77e450c3b        dfb546fe7394                               "/bin/sh -c '/usr/loc"   7 days ago          Up 7 days                               k8s_kube-scheduler_kube-scheduler-e2e-test-yjhong-master_kube-system_cfa6655f2f52a0a17806f3fc173be9bc_0

We no longer tag the image name with gcr.io/google_containers/kube-apiserver:. I don't know why.

[yujuhong]

@k8s-bot gci gce e2e test this

[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 42652, 42681, 42708, 42730)