Summary

Follow-up from PR #16416 (collect_set RESPECT NULLS). As noted by @rui-mo, the same pattern should be applied to collect_list:

• Remove kSparkCollectListIgnoreNulls QueryConfig
• Add a constant boolean argument to collect_list(x [, ignoreNulls]) matching the collect_set approach
• Use the Aggregate::setConstantInputs() hook to read the constant at initialization time

This aligns with Spark's CollectList expression which has an ignoreNulls parameter at the expression level, not a session-level config.

Reference: #16416 (comment)