Fix Copy circuit benchmark

[ChihChengLiang]

What command(s) is the bug in?

cargo test -p circuit-benchmarks --features benches bench_copy_circuit_prover -- --nocapture

Describe the bug

This is a follow-up for #1646 and #1686.

The benchmark for Copy circuit remains to be fixed.

Possible direction for investigation.

• The number of copy events is carefully chosen. Investigate the generate_full_events_block function
• Tweak block.circuits_params.max_rws and block.circuits_params.max_copy_rows

Concrete steps to reproduce the bug. If it's able reproduce via testool, please share test_id from jenkins report

No response