[SPARK-25716][SQL][MINOR] remove unnecessary collection operation in valid constraints generation

## What changes were proposed in this pull request?

Project logical operator generates valid constraints using two opposite operations. It substracts child constraints from all constraints, than union child constraints again. I think it may be not necessary.
Aggregate operator has the same problem with Project.

This PR try to remove these two opposite collection operations.

## How was this patch tested?

Related unit tests:
ProjectEstimationSuite
CollapseProjectSuite
PushProjectThroughUnionSuite
UnsafeProjectionBenchmark
GeneratedProjectionSuite
CodeGeneratorWithInterpretedFallbackSuite
TakeOrderedAndProjectSuite
GenerateUnsafeProjectionSuite
BucketedRandomProjectionLSHSuite
RemoveRedundantAliasAndProjectSuite
AggregateBenchmark
AggregateOptimizeSuite
AggregateEstimationSuite
DecimalAggregatesSuite
DateFrameAggregateSuite
ObjectHashAggregateSuite
TwoLevelAggregateHashMapSuite
ObjectHashAggregateExecBenchmark
SingleLevelAggregateHaspMapSuite
TypedImperativeAggregateSuite
RewriteDistinctAggregatesSuite
HashAggregationQuerySuite
HashAggregationQueryWithControlledFallbackSuite
TypedImperativeAggregateSuite
TwoLevelAggregateHashMapWithVectorizedMapSuite

Closes #22706 from SongYadong/generate_constraints.

Authored-by: SongYadong <song.yadong1@zte.com.cn>
Signed-off-by: gatorsmile <gatorsmile@gmail.com>

Author: SongYadong

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala

@@ -152,10 +152,10 @@ abstract class UnaryNode extends LogicalPlan {
   override final def children: Seq[LogicalPlan] = child :: Nil
 
   /**
-   * Generates an additional set of aliased constraints by replacing the original constraint
-   * expressions with the corresponding alias
+   * Generates all valid constraints including an set of aliased constraints by replacing the
+   * original constraint expressions with the corresponding alias
    */
-  protected def getAliasedConstraints(projectList: Seq[NamedExpression]): Set[Expression] = {
+  protected def getAllValidConstraints(projectList: Seq[NamedExpression]): Set[Expression] = {
     var allConstraints = child.constraints.asInstanceOf[Set[Expression]]
     projectList.foreach {
       case a @ Alias(l: Literal, _) =>
@@ -170,7 +170,7 @@ abstract class UnaryNode extends LogicalPlan {
       case _ => // Don't change.
     }
 
-    allConstraints -- child.constraints
+    allConstraints
   }
 
   override protected def validConstraints: Set[Expression] = child.constraints

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala

@@ -64,7 +64,7 @@ case class Project(projectList: Seq[NamedExpression], child: LogicalPlan)
   }
 
   override def validConstraints: Set[Expression] =
-    child.constraints.union(getAliasedConstraints(projectList))
+    getAllValidConstraints(projectList)
 }
 
 /**
@@ -595,7 +595,7 @@ case class Aggregate(
 
   override def validConstraints: Set[Expression] = {
     val nonAgg = aggregateExpressions.filter(_.find(_.isInstanceOf[AggregateExpression]).isEmpty)
-    child.constraints.union(getAliasedConstraints(nonAgg))
+    getAllValidConstraints(nonAgg)
   }
 }