*v9.0 only - See BACKPORT ticket*

Problem

Since SERVER-132505, when upgrading to Authoritative Shards, we clear the UNTRACKED state from the CSR, since it may be an non-authoritatively installed stale value.

This can result in commands like updateMany failing midway with a non-retriable QueryPlanKilled error as follows:

• FCV is 8.x (non-authoritative), "coll" is an UNTRACKED collection.
• An updateMany command updates 3 documents and yields.
• Concurrently the FCV is set to 9.0: This clears the CSR metadata for "coll" to UNKNOWN (since it may be a stale value).
• The updateMany command unyields and re-checks the shard version.
• The CSR is UNKNOWN, so this generates a retriable StaleConfig error.
• The StaleConfig is however converted to a non-retriable QueryPlanKilled error, since the update had partially executed (i.e. already modified documents).

A reproducer is attached.

NOTE: Retryable writes do not help here, since updateMany is not compatible with retryable writes.

Impact: updateMany queries on unsharded collections may fail with QueryPlanKilled error (with partially updated result) during FCV 8.x -> 9.0 upgrade.

Solution: Avoid clearing the UNTRACKED CSR state on the DB primary on FCV upgrade. This works since the primary's CSR always has valid (i.e. fresh, not stale) UNTRACKED CSR.