Evaluate the performance impact of getTreeInfo

[boutell]

We have get*Info methods for smaller subsets of the page tree, but calling getTreeInfo just once and then outputting breadcrumb, tabs and side nav turns out to run rather well. However we need to test this with a much larger database to see how the performance is with 1000 or more pages. We're not making objects and the query is raw PDO, so it may still turn out to be good.

Long term we should think about using the symfony function call cache to further accelerate these methods, clearing that cache when page objects are saved or deleted.

[boutell]

Also, consider whether getAccordionInfo could be the basis call instead of getTreeInfo, that would be a simple fix (double check whether they return an identical data structure)

[boutell]

We hit this, we no longer use getTreeInfo by default.