These tests

test/sql/json/test_json_copy_tpch.test_slow -- 1
test/sql/aggregate/group/test_group_by_parallel.test_slow -- 2
test/sql/parallelism/intraquery/depth_first_evaluation.test_slow -- 3

Were giving memory/storage issues in CI.

For (1.), I've reduced the TPC-H scale factor to 0.1 instead of 1. We're still testing what we want to test, so this shouldn't be an issue (TPC-H files are really large when exported to JSON).

For (2.), the setting PRAGMA verify_external; was triggering a lot of partitioning and spilling to test the external grouped aggregation behavior. It was spilling more than necessary because the HT size calculation was off a bit, especially when this setting was enabled.

For (3.), a slight increase to the memory limit in the test was enough to make it work again. We're still testing the behavior we want to.