[JENKINS-53353] - Do not cache results of View.getActions() (#3608)

* JENKINS-53353 Do not cache results of View.getActions()

Plugins that may affect the view, eg via TransientViewActionFactory
that get installed _after_ a `view` has been initally viewed
will not be able to add anything to the view if the results
of getActions() are cached.

* JENKINS-53353 Removed unnecessary synchronization

* JENKINS-53353 Whitespace

* JENKINS-53353 Restored (and deprecated) updateTransientActions

to maintain backwards compatibility.