Remove redundant copy from RocksDB get_cf() wrapper (#17529) (#17543)

(cherry picked from commit 983828a2a9)

Co-authored-by: steviez <steven@solana.com>

ledger/src/blockstore_db.rs

@@ -363,7 +363,7 @@ impl Rocks {
     }
 
     fn get_cf(&self, cf: &ColumnFamily, key: &[u8]) -> Result<Option<Vec<u8>>> {
-        let opt = self.0.get_cf(cf, key)?.map(|db_vec| db_vec.to_vec());
+        let opt = self.0.get_cf(cf, key)?;
         Ok(opt)
     }