Prow sub can work with GitHub app

[chaodaiG]

No description provided.

[chaodaiG]

/assign @alvaroaleman
/cc @listx

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: chaodaiG

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

The pull request process is described here

Needs approval from an approver in each of these files:

• prow/OWNERS [chaodaiG]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[listx]

/lgtm

[alvaroaleman]

This shouldnt be needed, it happens in the flagutil when you call GitHubClientWithLogFields:

test-infra/prow/flagutil/github.go

Lines 272 to 274 in ef5dc9a

	if err := secret.Add(o.AppPrivateKeyPath); err != nil {
	return nil, fmt.Errorf("failed to add the the key from --app-private-key-path to secret agent: %w", err)
	}

Below is another check for flagOptions.github.TokenPath , that one needs to also allow apps auth

[chaodaiG]

ah. right. that's strange then. I'll take another looks

[chaodaiG]

found it, fixing in #24317, and by the way removing duplicated logic in the PR