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

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

**Tasks:** io.kestra.plugin.azure.aifoundry.RunAgent

**Why:** Starts an AI Foundry agent run and polls until terminal status; no kill()/stop() to cancel the remote run when the execution is killed.

**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.

Start with io.kestra.plugin.azure.aifoundry.RunAgent and compare its polling behavior with the kill()/stop() implementation in io.kestra.plugin.gcp.bigquery.AbstractBigquery. Trace how the agent run is started and polled, then implement cancellation for the poll loop and remote run as appropriate. Done means killed executions no longer leave the AI Foundry run polling or running remotely.

Written by the indexing model from the issue text.