Presence of initialSyncStatus in replSetGetStatus consumes too much FTDC space

SERVER-7019 turned on initialSyncStatus in replSetGetStatus by default, and that causes it to be included in FTDC. However this means that for a user with a very large number of collections there will be a very large number of keys and a lot of expensive schema changes in FTDC, using a very large amount of space and becoming unworkably large. This causes problems for consuming tools, and means that FTDC can roll over before initial sync completes.

We should exclude the initialSyncStatus section from in replSetGetStatus FTDC.