We are directly inserting the Queue, but instead of just blindly copying
what was in the old document, apply the $pullAll that we would have
applied if this were an Update. Because we are creating the stash
document from scratch, we don't need to ask Mongo to do the work.

Essentially, we don't have to do both Insert and Remove, because one of
them must have been done in order to do the other.

This way, a series of only Insert and Remove operations won't cause the
txn-queue to get out of hand.

It turns out that I missed we had just reread the document as part of
the 'add txn-insert' or 'add txn-remove' to the document. That gives us
an updated txn-queue that needs to be handled. Since we are now cleaning
directly on the txn-queue instead of the cached queue docs, go ahead and
do it on both Insert and Remove.