dbHash can deadlock with an index build that is being aborted in the following way:

• dbHash opens a read snapshot at time T
• Index build aborts, and while holding a Collection X lock, tries to set ghost commit timestamp to T
• dbHash waits for a Collection IS lock
• Index build waits for dbHash reader to abort

We can consider modifying dbHash to not wait on a collection lock while holding open a snapshot.

This only affects 4.4 because the ghost timestamp code was removed in 5.0 in SERVER-47867