Upgrading pipelines operator from 1.4.1 to 1.6.2 causes builds to fail

After upgrade from Pipelines operator 1.4.1 to 1.6.2 and that caused the following errors and eventListener was not working (bitbucket updates were not kicking in builds), but customer was able to manually run the builds.

./core/events.yaml: message: 'Failed to update status for "qcontrol-services": admission webhook "webhook.triggers.tekton.dev" denied the request: mutation failed: cannot decode incoming old object: json: unknown field "podTemplate"'

Customer was able to create a new EventListener (in the revised format that did not include podTemplate) and the new EL was working fine.

However customer cannot delete the old EL due to the following errors.

Error from server (BadRequest): admission webhook "webhook.triggers.tekton.dev" denied the request: mutation failed: cannot decode incoming new object: json: unknown field "podTemplate"

Customer then tried the following steps provided by engineering and the issue still persists. The OC command says the EL as getting deleted, but the console UI still shows it, but the delete option in UI is now disabled.

We tried to provide more steps to fix the issue, but Cu is raising concern and asked if the steps were tested.

I am opening this Jira for two reasons.

1. to investigate and see if blocking upgrade 1.4. to 1.6 (skipping the 1.5) is possible since that is what seem to have caused the issue. If this effort is high or is not possible then we can create a KCS based out of the next item.

2. and to reproduce the issue in house and provide the steps to fix the issue