[SPARK-13473][SQL] Simplifies PushPredicateThroughProject

## What changes were proposed in this pull request?

This is a follow-up of PR apache#11348.

After PR apache#11348, a predicate is never pushed through a project as long as the project contains any non-deterministic fields. Thus, it's impossible that the candidate filter condition can reference any non-deterministic projected fields, and related logic can be safely cleaned up.

To be more specific, the following optimization is allowed:

```scala
// From:
df.select('a, 'b).filter('c > rand(42))
// To:
df.filter('c > rand(42)).select('a, 'b)
```

while this isn't:

```scala
// From:
df.select('a, rand('b) as 'rb, 'c).filter('c > 'rb)
// To:
df.filter('c > rand('b)).select('a, rand('b) as 'rb, 'c)
```

## How was this patch tested?

Existing test cases should do the work.

Author: Cheng Lian <[email protected]>

Closes apache#11864 from liancheng/spark-13473-cleanup.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala

@@ -891,29 +891,7 @@ object PushPredicateThroughProject extends Rule[LogicalPlan] with PredicateHelpe
         case a: Alias => (a.toAttribute, a.child)
       })
 
-      // Split the condition into small conditions by `And`, so that we can push down part of this
-      // condition without nondeterministic expressions.
-      val andConditions = splitConjunctivePredicates(condition)
-
-      val (deterministic, nondeterministic) = andConditions.partition(_.collect {
-        case a: Attribute if aliasMap.contains(a) => aliasMap(a)
-      }.forall(_.deterministic))
-
-      // If there is no nondeterministic conditions, push down the whole condition.
-      if (nondeterministic.isEmpty) {
-        project.copy(child = Filter(replaceAlias(condition, aliasMap), grandChild))
-      } else {
-        // If they are all nondeterministic conditions, leave it un-changed.
-        if (deterministic.isEmpty) {
-          filter
-        } else {
-          // Push down the small conditions without nondeterministic expressions.
-          val pushedCondition =
-            deterministic.map(replaceAlias(_, aliasMap)).reduce(And)
-          Filter(nondeterministic.reduce(And),
-            project.copy(child = Filter(pushedCondition, grandChild)))
-        }
-      }
+      project.copy(child = Filter(replaceAlias(condition, aliasMap), grandChild))
   }
 
 }