Add a `cascade` field to the pipeline bundle resource that controls whether
destroying a pipeline also deletes its datasets (materialized views, streaming
tables, and views). When unset, the server default applies (cascade); set
`cascade: false` to retain the datasets on destroy.
The field is delete-time only: it is not part of the pipeline spec, so it is
never sent on create/update. The direct engine persists it in state (via a
PipelineState wrapper around CreatePipeline, mirroring the sql_warehouse
lifecycle pattern) and reads it at delete time, force-sending cascade so an
explicit false survives query-string omitempty (honored for query params as of
databricks-sdk-go v0.152.0). A cascade-only change is a state-only update with
no pipeline API call. cascade is classified input_only so it does not show
remote drift.
The terraform engine drops the field for now: the pinned provider has no such
attribute yet (pending terraform-provider-databricks#5860), so terraform-engine
support is a follow-up.
Co-authored-by: Isaac
Used for testing: #5846