[release-3.9] Fix initContainer name lookup for ImageChange trigger

[openshift-cherrypick-robot]

This is an automated cherry-pick of #18785

/assign liggitt

[eparis]

/retest

[eparis]

/retest
/hold
(hold until 3.9 GA, then anyone may clear the hold)

[smarterclayton]

/retest

[eparis]

/hold cancel

[smarterclayton]

/approve
/lgtm

Measurable impact to origin users

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: openshift-cherrypick-robot, smarterclayton

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:

• pkg/image/OWNERS [smarterclayton]

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

[openshift-ci-robot]

@openshift-cherrypick-robot: The following test failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
ci/openshift-jenkins/extended_networking_minimal	a7adc66	link	/test extended_networking_minimal

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/test-infra repository. I understand the commands that are listed here.

[eparis]

/retest