Need to update rhel version from rhel8 to rhel9 from 4.16 version clusters.

Link: https://docs.openshift.com/container-platform/4.16/support/gathering-cluster-data.html#gathering-data-specific-features_gathering-cluster-data

Table 1. Supported must-gather images

registry.redhat.io/openshift4/ose-secrets-store-csi-mustgather-rhel8:v<installed_version_secret_store> => 
oc adm must-gather --image="registry.redhat.io/openshift4/ose-secrets-store-csi-mustgather-rhel9:v4.16"

4.16