hypershift 4.13 prow jobs failed because of spec.pullSecret is immutable now

# QE prow CI job update hostedcluster.spec.pullSecret for some qe catalog source configurations. 4.13 jobs failed with error msg:

Error from server (HostedCluster.spec.pullSecret.name: Invalid value: "9509a26c339de31aa3c9-pull-secret-new": Attempted to change an immutable field): admission webhook "hostedclusters.hypershift.openshift.io" denied the request: HostedCluster.spec.pullSecret.name: Invalid value: "9509a26c339de31aa3c9-pull-secret-new": Attempted to change an immutable field

4.13

4.13 job:
https://qe-private-deck-ci.apps.ci.l2s4.p1.openshiftapps.com/view/gs/qe-private-deck/pr-logs/pull/openshift_release/41339/rehearse-41339-periodic-ci-openshift-openshift-tests-private-release-4.13-amd64-nightly-aws-ipi-ovn-hypershift-guest-p1-f7/1689831180221812736

see the above job

job failed to config pull secret for hostedcluster

job could run successfully

1. The 4.14  hypershift QE CI jobs were successfully executed with the same codes.
2. I can update 4.13 hostedcluster spec.pullSecret in my local hypershift env.

It seems to be caused by some limitation only in prow?