Limit the DML memory to avoid frontend OOM

[cyliu0]

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

The frontend node will be OOM during ch-benchmark test loading data. https://buildkite.com/risingwave-test/ch-benchmark-risingwave/builds/17#018e7b25-ca57-4dcb-9792-2edb10740004

@chenzl25 suggest we could limit the memory of DML execution to reduce the frontend OOM.

Describe the solution you'd like

No response

Describe alternatives you've considered

No response

Additional context

No response

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