### What changes were proposed in this pull request?
I discovered from review discussion - https://github.com/apache/spark/pull/31630#discussion_r581774000 , that we can eliminate LEFT ANTI join (with no join condition) to empty relation, if the right side is known to be non-empty. So with AQE, this is doable similar to https://github.com/apache/spark/pull/29484 .
### Why are the changes needed?
This can help eliminate the join operator during logical plan optimization.
Before this PR, [left side physical plan `execute()` will be called](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastNestedLoopJoinExec.scala#L192), so if left side is complicated (e.g. contain broadcast exchange operator), then some computation would happen. However after this PR, the join operator will be removed during logical plan, and nothing will be computed from left side. Potentially it can save resource for these kinds of query.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Added unit tests for positive and negative queries in `AdaptiveQueryExecSuite.scala`.
Closes#31641 from c21/left-anti-aqe.
Authored-by: Cheng Su <chengsu@fb.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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