[make_cluster] does not allow custom node_type_id

[b0lle]

Hey,

pytester/src/databricks/labs/pytester/fixtures/compute.py

Line 108 in 64fb32f

if "instance_pool_id" not in kwargs:

does not allow a custom node_type_id, if the "instance_pool_id" is not given. In my point of view this doesn't make sense, still I want to be able to match my cluster_policies requirements.