remove the outdate comments in tryRegisterWithAPIServer

[stewart-yu]

What this PR does / why we need it:
some judgement about ExternalID removed in #61877, so remove the outdate comments in tryRegisterWithAPIServer

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:

Release note:

NONE

[stewart-yu]

/retest

[stewart-yu]

/cc @dchen1107 @kubernetes/sig-node-pr-reviews

[yujuhong]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: stewart-yu, yujuhong

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[k8s-github-robot]

/test all [submit-queue is verifying that this PR is safe to merge]

[stewart-yu]

/retest

[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 66593, 66727, 66558). If you want to cherry-pick this change to another branch, please follow the instructions here.

[k8s-ci-robot]

@stewart-yu: The following test failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-kubernetes-local-e2e-containerized	ffbd7b2	link	/test pull-kubernetes-local-e2e-containerized

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.

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