RU: The ability of resource control to limit large SQL is week

## Enhancement Task

The ability of resource control to limit large SQL is weak because RU consumption is deducted when the KV request returns, causing limitations on the resource usage of related SQL based on ru_per_sec to be ineffective when there are high concurrent KV requests or a single KV request consumes a large amount of RUs.
From the RU(MAX) panel in the resource control panel, it can be seen that the maximum RU consumption of related resource groups frequently exceeds ru_per_sec, indicating that large SQL queries are not effectively restricted.

Start by locating the resource-control implementation responsible for deducting RU consumption after KV requests return, then inspect how the RU(MAX) panel reflects those limits. Define behavior for concurrent KV requests and requests with large RU consumption, and verify that related SQL resource groups remain bounded by ru_per_sec.

Written by the indexing model from the issue text.