feat(frontend): add max_batch_queries_per_frontend_node config

[kwannoel]

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What's changed and what's your intention?

We currently have distributed_query_limit, but that just limits the number of queries per session.
What we want instead is to limit the number of concurrent batch queries cluster wide.

The usecase for it is when there's some batch query which triggers OOM, we want to limit the number of this batch query.

Because meta node doesn't really manage batch queries, we have to do it elsewhere. We choose to do it in frontend, because there's typically only 1 frontend node, so effectively, it's a cluster wide limit on the number of batch queries.

We simply add the permit to QueryExecution which must be dropped (deleted), when the execution ends either due to cancel, errors, or completion.

I have tested it locally in the following way:

./risedev d full-with-batch-query-limit

Execute:

CREATE TABLE t(v1 int);
INSERT INTO t select 1 from generate_series(1, 10000);

Start 2 long running queries:

./risedev psql -c 'select count(*) from t x join t y using(v1); &
./risedev psql -c 'select count(*) from t x join t y using(v1); &

Execute another query in local mode:

select 1;

Can execute without issues.

Execute a query which should be pretty fast:

select count(*) from t;

It will now take a long time.

Cancel the previous 2 queries, and we can continue running queries.

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[kwannoel]

Merge it in first, urgent for customer's usecase.

[kwannoel]

I will change the semantics slightly. Since these batch queries are not directly ran by a user, but rather by dashboard, I think we can just let the queries block the session, since they will not be retried automatically.