Fix Kafka consumer not being closed on error in ConsumeFromTopicOperator

[TimurRakhmatullin86]

ConsumeFromTopicOperator.execute only called consumer.close() on the happy path. If apply_function / apply_function_batch raised, or consumer.consume() / consumer.commit() failed, the operator leaked the consumer: the group member stays registered on the broker until session.timeout.ms expires (delaying partition rebalance for the rest of the consumer group), and the underlying librdkafka handle keeps its sockets and background threads alive in the worker until GC.

This wraps the processing loop in try/finally so the consumer is always closed:

• the loop body is unchanged (re-indent only);
• offset commits stay inside try, so nothing is committed for a failed batch;
• close() in finally is guarded with a log.warning, mirroring the AwaitMessageTrigger consumer cleanup from Add cleanup to Kafka AwaitMessageTrigger for consumer management #64612 — close() performs a final synchronous offset commit when enable.auto.commit is on (the librdkafka default), so it can itself raise and would otherwise replace the original processing error as the task failure reason.

Tests: test_execute_closes_consumer_when_apply_function_raises (fails without the fix) and test_execute_does_not_mask_error_when_close_raises.