Change stop watchdog log to verbose info

[DavidXU12345]

When running test, stopping log for watchdog spams the test log, let's make it verbose level 4 so that it won't show during test.

Is this a bug fix or adding new feature?
Minor change

What is this PR about? / Why do we need it?
the watchdog stopping... log makes it difficult to read the test log, let's make it klog.V(4).Info so that it won't be printed out during test

What testing is done?
N/A

[k8s-ci-robot]

Hi @DavidXU12345. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[DavidXU12345]

/ok-to-test

[dankova22]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dankova22, DavidXU12345

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[k8s-ci-robot]

@DavidXU12345: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-aws-efs-csi-driver-e2e	0b76202	link	unknown	/test pull-aws-efs-csi-driver-e2e

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.