Openshift apiserver: Make the global pullsecret accessible

[alvaroaleman]

The openshift-apiserver doesn't access the global pullsecret from the
api but reads it from /var/lib/kubelet/config.json. Without this change,
imagestream imports that rely on the global pull secret don't work.

This fixes the "[sig-builds][Feature:Builds] imagechangetriggers
imagechangetriggers should trigger builds of all types" conformance
test.

Ref https://issues.redhat.com/browse/HOSTEDCP-257

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alvaroaleman

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[csrwng]

nice!
/lgtm

[alvaroaleman]

/cherrypick release-4.8

[openshift-cherrypick-robot]

@alvaroaleman: once the present PR merges, I will cherry-pick it on top of release-4.8 in a new PR and assign it to you.

In response to this:

/cherrypick release-4.8

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.

[openshift-bot]

/retest-required

Please review the full test history for this PR and help us cut down flakes.

[openshift-bot]

/retest-required

Please review the full test history for this PR and help us cut down flakes.

[alvaroaleman]

/retest

[openshift-bot]

/retest-required

Please review the full test history for this PR and help us cut down flakes.

[openshift-bot]

/retest-required

Please review the full test history for this PR and help us cut down flakes.

[openshift-cherrypick-robot]

@alvaroaleman: #606 failed to apply on top of branch "release-4.8":

Applying: Openshift apiserver: Make the global pullsecret accessible
Using index info to reconstruct a base tree...
M	control-plane-operator/controllers/hostedcontrolplane/oapi/deployment.go
Falling back to patching base and 3-way merge...
Auto-merging control-plane-operator/controllers/hostedcontrolplane/oapi/deployment.go
CONFLICT (content): Merge conflict in control-plane-operator/controllers/hostedcontrolplane/oapi/deployment.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Openshift apiserver: Make the global pullsecret accessible
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

In response to this:

/cherrypick release-4.8

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.