This does not affect a released version of 4.2

During both startup and index creation, we initialize an index's multikey state by calling _catalogIsMultikey. This should initialize directly from the durable catalog, but there is an early-return that checks the _isMultikeyForRead flag first. At this point, _isMultikeyForRead hasn't been initialized; it gets initialized immediately afterward.

This can cause a bug where an index will not get updated to multikey when it should.

We should be able to eliminate this early check entirely, which is the case on other branches.