Function raftstore::store::clear_meta

pub fn clear_meta<EK, ER>(
    engines: &Engines<EK, ER>, 
    kv_wb: &mut EK::WriteBatch, 
    raft_wb: &mut ER::LogBatch, 
    region_id: u64, 
    raft_state: &RaftLocalState
) -> Result<()> where
    EK: KvEngine,
    ER: RaftEngine, 

Delete all meta belong to the region. Results are stored in wb.