Syncgateway GET RevCache (~25%)degradation on single node in build 2.5.0-118

Observing  ~25% degradation in GET RevCache scenario on single node test 

Change Log 

• Commit:

c81b04af6defd248d69092d11d8f719caf840c4f in build: 2.5.0-118

Store attachment and expiry metadata in rev cache (#3831)

• Store attachment and expiry metadata in rev cache Avoids additional bucket GET when retrieving attachment or expiry data when document is resident in the rev cache.