Image pull Secrets should be added to service Account pipeline to push image to private registry

Description of problem:

Assumpitons:
1. pipelines operator should be installed
2. Create a new namespace/project

Via +Add-flow when user selects pipelines, while starting pipeline from UI, try changing image location to private image registry eg: `quay.io/<usrname>/<image-name>`

Select Advanced options -> Add secrets -> (provide necessary details ) by selecting authentication type as image credentials once you add secrets by default it gets attached to service account pipeline.

Seems when user tries to add secrets to service account, it's getting attached to sa to `pull` by default

eg:  here is oc command how add our secrets to service account explicitly  at run time

oc secrets link serviceaccount/<sa> secrets/<pull_secret_name> --for=pull,mount

Note: with existing build user can pull image from private registry but won't be able to push to it.

Actual results:

secrets:
  - name: pipeline-token-88mw6
  - name: pipeline-dockercfg-pv68m
  - name: quay-sec
imagePullSecrets:
  - name: pipeline-dockercfg-pv68m

Expected results:

secrets:
  - name: pipeline-token-88mw6
  - name: pipeline-dockercfg-pv68m
  - name: quay-sec
imagePullSecrets:
  - name: pipeline-dockercfg-pv68m
  - name: quay-sec
 

Reproducibility : Always

Build Details: ocp 4.6, openshift-pipelines 1.2.1