Removed opReadConcernCounters from serverStatus.
Added a new metric readConcernCounters in serverStatus to track readConcern usages for reads.
readConcernCounters.nonTransactionOps tracks readConcern for reads outside of transactions.
readConcernCounters.transactionOps tracks readConcern for reads inside transactions.
snapshot.withoutClusterTime tracks usages of readConcern: {level: "snapshot"}.
snapshot.withClusterTime tracks usages of readConcern: {level: "snapshot", atClusterTime: ...} (i.e. readConcern snapshot with a user specified point in time).
See the server ticket for all the fields in the document.