[SCT]: Extend to replace/remove nemesis to run operations in paralel

[aleksbykov]

Issue description

Raft topology feature support parallel operations: bootstrap, decommission, replace, remove. Bootstrap, decommission already implemented. Need to add support of parallel replace/remove to current nemesis.

Expected behavior: [What you expected to happen] With current sct infrastructure replace/remove node disrupt nemesis have to run for several nodes in parallel.

• Use nemesis_add_node_cnt or add_node_cnt how many node to replace/replace
• Check that enough nodes for quorum.
• Check replication factor of keyspaces, and skip several node replace if quorum could be lost
• stop/kill required number of nodes.
• Run replace operations.