Take in account replicationFactor with dropSamplesOnOverload=true

[f41gh7]

Is your feature request related to a problem? Please describe

With the enabled dropSamplesOnOverload setting, samples are dropped before the replication factor was applied, which results in complete data loss instead of data loss only for unavailable vmstorage replica. This confuses users and is misaligned with intuitive understanding of this setting.

Describe the solution you'd like

Redesign the current replication mechanism to allow dropping samples after the replication, so data will be dropped only for overloaded vmstorage node. It should help to prevent cluster degradation when one of vmstorage nodes is slow and other replicas could process metrics ingestion.