[SPARK-51119][SQL][FOLLOW-UP] Readers on executors resolving EXISTS_D…

…EFAULT should not call catalogs

### What changes were proposed in this pull request?
 Code cleanup for #49840.  Literal#fromSQL should be the inverse of Literal#sql.  The cast handling is an artifact of the calling ResolveDefaultColumns object that adds the cast when making EXISTS_DEFAULT, so its handling is moved to ResolveDefaultColumns as well.

### Why are the changes needed?
Code cleanup

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
Existing tests

### Was this patch authored or co-authored using generative AI tooling?
No

Closes #49881 from szehon-ho/SPARK-51119-follow.

Authored-by: Szehon Ho <szehon.apache@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala

@@ -268,6 +268,9 @@ object Literal {
       s"but class ${Utils.getSimpleName(value.getClass)} found.")
   }
 
+  /**
+   * Inverse of [[Literal.sql]]
+   */
   def fromSQL(sql: String): Expression = {
     CatalystSqlParser.parseExpression(sql).transformUp {
       case u: UnresolvedFunction =>
@@ -278,10 +281,6 @@ object Literal {
         assert(u.orderingWithinGroup.isEmpty)
         assert(!u.isInternal)
         FunctionRegistry.builtin.lookupFunction(FunctionIdentifier(u.nameParts.head), u.arguments)
-    } match {
-      case c: Cast if c.needsTimeZone =>
-        c.withTimeZone(SQLConf.get.sessionLocalTimeZone)
-      case e: Expression => e
     }
   }
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/ResolveDefaultColumnsUtil.scala

@@ -320,14 +320,20 @@ object ResolveDefaultColumns extends QueryErrorsBase
   }
 
   /**
-   * Analyze EXISTS_DEFAULT value.  This skips some steps of analyze as most of the
-   * analysis has been done before.
+   * Analyze EXISTS_DEFAULT value.  EXISTS_DEFAULT value was created from CURRENT_DEFAQULT
+   * via [[analyze]] and thus this can skip most of those steps.
    */
   private def analyzeExistenceDefaultValue(field: StructField): Expression = {
     val defaultSQL = field.metadata.getString(EXISTS_DEFAULT_COLUMN_METADATA_KEY)
 
     // Parse the expression.
-    val expr = Literal.fromSQL(defaultSQL)
+    val expr = Literal.fromSQL(defaultSQL) match {
+      // EXISTS_DEFAULT will have a cast from analyze() due to coerceDefaultValue
+      // hence we need to add timezone to the cast if necessary
+      case c: Cast if c.needsTimeZone =>
+        c.withTimeZone(SQLConf.get.sessionLocalTimeZone)
+      case e: Expression => e
+    }
 
     // Check invariants
     if (expr.containsPattern(PLAN_EXPRESSION)) {