[MINOR][SQL][TESTS] Remove redundant space at PropagateEmptyRelationSuite class definition

### What changes were proposed in this pull request?

Followup of #48149, minor minor style fix

### Why are the changes needed?

Style

### Does this PR introduce _any_ user-facing change?

No

### How was this patch tested?

As long as it compiles

### Was this patch authored or co-authored using generative AI tooling?

No

Closes #49911 from WweiL/minor.

Authored-by: Wei Liu <wei.liu@databricks.com>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>

Author: WweiL

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/PropagateEmptyRelationSuite.scala

@@ -30,7 +30,7 @@ import org.apache.spark.sql.catalyst.types.DataTypeUtils
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types.{IntegerType, MetadataBuilder}
 
-class   PropagateEmptyRelationSuite extends PlanTest {
+class PropagateEmptyRelationSuite extends PlanTest {
   object Optimize extends RuleExecutor[LogicalPlan] {
     val batches =
       Batch("PropagateEmptyRelation", FixedPoint(1),