[SPARK-19861][SS] watermark should not be a negative time.

## What changes were proposed in this pull request?

`watermark` should not be negative. This behavior is invalid, check it before real run.

## How was this patch tested?

add new unit test.

Author: uncleGen <hustyugm@gmail.com>
Author: dylon <hustyugm@gmail.com>

Closes #17202 from uncleGen/SPARK-19861.

(cherry picked from commit 30b18e69)
Signed-off-by: Shixiong Zhu <shixiong@databricks.com>