Audit all background tasks and decide which should conflict with replication application

Currently all background tasks that ever acquire the global lock in any mode conflict with secondary application due to the PBWM lock. SERVER-26005 will make the FTDC thread not conflict. We should also audit all other background jobs and decide which ones should be able to run concurrently with a replication batch. For example, the ClientCursorMonitor thread should be able to run concurrently with replication, but the readConcern=majority SnapshotThread should not.