[SPARK-22141][SQL] Propagate empty relation before checking Cartesian products

## What changes were proposed in this pull request?

When inferring constraints from children, Join's condition can be simplified as None.
For example,
```
val testRelation = LocalRelation('a.int)
val x = testRelation.as("x")
val y = testRelation.where($"a" === 2 && !($"a" === 2)).as("y")
x.join.where($"x.a" === $"y.a")
```
The plan will become
```
Join Inner
:- LocalRelation <empty>, [a#23]
+- LocalRelation <empty>, [a#224]
```
And the Cartesian products check will throw exception for above plan.

Propagate empty relation before checking Cartesian products, and the issue is resolved.

## How was this patch tested?

Unit test

Author: Wang Gengliang <ltnwgl@gmail.com>

Closes #19362 from gengliangwang/MoveCheckCartesianProducts.