Previously, datagrids would attach additional event handler for
infoboxes on top of the initial event handler. This would result in two
fetches for all infoboxes in the datagrid until the first refresh. Now
we set an attribute on elements which can have infoboxes attached them
when the infobox handler has been added so that it will not be added
again.

Testing Done:
Verified infoboxes in datagrids are no longer requested twice.

Reviewed at https://reviews.reviewboard.org/r/8568/