structural witness max length check under field arithmetics

[hero78119]

1. respective check in rust verifier not found in recursion verifier
   

   ceno/ceno_zkvm/src/scheme/verifier.rs

   Lines 484 to 507 in ff341ef

   	cs.r_table_expressions
   	.iter()
   	.chain(&cs.w_table_expressions)
   	.for_each(|set_table_expr| {
   	// iterate through structural witins and collect max round.
   	let num_vars = set_table_expr
   	.table_spec
   	.len
   	.map(ceil_log2)
   	.unwrap_or_else(|| {
   	set_table_expr
   	.table_spec
   	.structural_witins
   	.iter()
   	.map(|StructuralWitIn { witin_type, .. }| {
   	let hint_num_vars = log2_num_instances;
   	assert!((1 << hint_num_vars) <= witin_type.max_len());
   	hint_num_vars
   	})
   	.max()
   	.unwrap_or(log2_num_instances)
   	});
   	assert_eq!(num_vars, log2_num_instances);
   	});

@darth-cy am I correct?

2. This check seems invalid under prime(ext) field because of wrapping logic