fix magic string for runtime type

[andyxning]

What this PR does / why we need it:
This PR correct the magic string about container runtime to the constants.
Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:
This PR correct the magic string about container runtime to the constants.
Release note:

None

[andyxning]

/assign @yujuhong
/cc @derekmahar @dims since both of you modified this file recently.

[andyxning]

/retest

[andyxning]

/cc @mindprince Since it seems that you can help to give this PR a mark to make it available to merge for 1.9 milestone.

[ncdc]

1.9 is almost ready to be released. I recommend this wait until code freeze on master lifts, and this can then make it in for 1.10.

[feiskyer]

/lgtm

[andyxning]

1.9 is almost ready to be released. I recommend this wait until code freeze on master lifts, and this can then make it in for 1.10.

SGTM.

[yujuhong]

/approve no-issue

This can wait until 1.9 is cut.

[andyxning]

@yujuhong As stated in the mailing list, v1.9 has been lifted and master branch is open for v1.10. Could we merge this?

[yujuhong]

@yujuhong As stated in the mailing list, v1.9 has been lifted and master branch is open for v1.10. Could we merge this?

Yes, but there is nothing we need to do since the submit queue should pick this up automatcally

[andyxning]

Ping @feiskyer @ncdc @yujuhong for lgtm and approve. :)

[feiskyer]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andyxning, feiskyer, yujuhong

Associated issue requirement bypassed by: yujuhong

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

Needs approval from an approver in each of these OWNERS Files:

• pkg/kubelet/OWNERS [yujuhong]

You can indicate your approval by writing /approve in a comment
You can cancel your approval by writing /approve cancel in a comment

[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 57148, 57123, 57091, 57141, 57131). If you want to cherry-pick this change to another branch, please follow the instructions here.