plugin-gcp: kill()/stop() not implemented on killable/pollable tasks

Sub-issue of kestra-io/kestra-ee#10964.

**Tasks:** io.kestra.plugin.gcp.dataform.InvokeWorkflow, io.kestra.plugin.gcp.pubsub.Consume

**Why:** InvokeWorkflow polls a Dataform workflow invocation to completion; Consume runs a long-lived Pub/Sub pull loop. Neither overrides kill()/stop().

**Fix:** override `kill()` and/or `stop()` on these task classes to cancel the poll loop / close the consumer / cancel the remote job. See `io.kestra.plugin.gcp.bigquery.AbstractBigquery` for a reference implementation.

Read the InvokeWorkflow and Consume task classes, then compare their lifecycle handling with io.kestra.plugin.gcp.bigquery.AbstractBigquery. Confirm how kill() and stop() should cancel the Dataform poll loop, close the Pub/Sub consumer, or cancel the remote job. Done means both tasks respond correctly to the relevant lifecycle calls without leaving work running.

Written by the indexing model from the issue text.