Enable the MultiIndexBlock, which is the index builder code, to 1) update the index build information currentOp reports 2) automatically form a blob of BSON for currentOp reports drawing from MultiIndexBlock internal field information.
- causes
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                    SERVER-39974 Move MultiIndexBlock::_updateCurOpOpDescription into the IndexBuildsCoordinator -         
- Closed
 
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- related to
- 
                    SERVER-37964 Track the wall clock time when an index build begins -         
- Closed
 
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