[SPARK-19268][SS] Disallow adaptive query execution for streaming queries

## What changes were proposed in this pull request?

As adaptive query execution may change the number of partitions in different batches, it may break streaming queries. Hence, we should disallow this feature in Structured Streaming.

## How was this patch tested?

`test("SPARK-19268: Adaptive query execution should be disallowed")`.

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #16683 from zsxwing/SPARK-19268.

(cherry picked from commit 60bd91a3)
Signed-off-by: Shixiong Zhu <shixiong@databricks.com>