Fix transaction pruning in tx-pool (#6276)

The `tree_route` generated by the import notification is only from the
old best block to the new best parent. This means, it does not contain
the new best block in `enacted()`. We need to prune the transactions of
the new best block "manually" to fix this bug.

Besides that, this pr also changed the `id` parameter of the `NewBlock`
chain event to `hash`. The hash of a block is unique in contrast to the
block number. (Block id can either be number or hash)

substrate/bin/node/cli/src/service.rs

@@ -490,7 +490,7 @@ mod tests {
 					service.transaction_pool().maintain(
 						ChainEvent::NewBlock {
 							is_new_best: true,
-							id: parent_id.clone(),
+							hash: parent_header.hash(),
 							tree_route: None,
 							header: parent_header.clone(),
 						},