Move CloudList.setOwner call from Jenkins.loadTasks to load

[jglick]

In CloudBees CI we noticed an issue whereby after reloading $JENKINS_HOME/config.xml via Jenkins.load() (exposed as Loadable in #8544), Jenkins.clouds had a blank (NOOP) owner. This meant that subsequent changes to the cloud list were not saved. loadTasks (which calls load in its loadJenkins task) fixed up the owner but just load did not.

Testing done

Covered by a regression test in CloudBees CI. I could try to construct something analogous here though I am not sure how compelling it would be out of context.

Proposed changelog entries

• Setting a proper owner for Jenkins.clouds after Jenkins.load().

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[NotMyFault]

/label ready-for-merge

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