feat(openmldb-sdk): Improve multiple clients query and multiple result set

**Is your feature request related to a problem? Please describe.**

Now we can support simple queries under online execute mode on ClusterOpenMLDB. The problem is we perform distributive batch queries with blocking.
In this issue, we are going to improve the performance of the distributive online batch query by running SQL queries async or parallelly.

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Look at the online execute mode and batch query handling in the OpenMLDB SDK codebase, likely in the client or query execution modules. Understand how queries are currently distributed and blocked. Investigate async or parallel execution patterns in the codebase. The goal is to modify the query execution flow to run SQL queries concurrently and return multiple result sets efficiently.

Written by the indexing model from the issue text.