[MINOR] Remove redundant return

### What changes were proposed in this pull request?
Remove redundant return in scala code.

### Why are the changes needed?
Syntactic simplification.

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

### How was this patch tested?
Pass GA.

Closes apache#37148 from panbingkun/remove_redundance_return.

Authored-by: panbingkun <pbk1982@gmail.com>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>

core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala

@@ -892,7 +892,7 @@ private[spark] class DechunkedInputStream(wrapped: InputStream) extends InputStr
       }
     }
     assert(destSpace == 0 || remainingInChunk == -1)
-    return destPos - off
+    destPos - off
   }
 
   override def close(): Unit = wrapped.close()

core/src/main/scala/org/apache/spark/serializer/SerializationDebugger.scala

@@ -123,7 +123,7 @@ private[spark] object SerializationDebugger extends Logging {
         }
         i += 1
       }
-      return List.empty
+      List.empty
     }
 
     /**
@@ -145,7 +145,7 @@ private[spark] object SerializationDebugger extends Logging {
         }
         i += 1
       }
-      return List.empty
+      List.empty
     }
 
     private def visitSerializable(o: Object, stack: List[String]): List[String] = {
@@ -212,7 +212,7 @@ private[spark] object SerializationDebugger extends Logging {
         }
         i += 1
       }
-      return List.empty
+      List.empty
     }
 
     /**
@@ -249,7 +249,7 @@ private[spark] object SerializationDebugger extends Logging {
       } else {
         visited ++= innerObjectsCatcher.outputArray
       }
-      return List.empty
+      List.empty
     }
   }
 

core/src/main/scala/org/apache/spark/shuffle/sort/SortShuffleWriter.scala

@@ -80,9 +80,9 @@ private[spark] class SortShuffleWriter[K, V, C](
       }
       stopping = true
       if (success) {
-        return Option(mapStatus)
+        Option(mapStatus)
       } else {
-        return None
+        None
       }
     } finally {
       // Clean up our sorter, which may have its own intermediate files

core/src/main/scala/org/apache/spark/storage/BlockManager.scala

@@ -1831,7 +1831,7 @@ private[spark] class BlockManager(
     }
 
     logDebug(s"block $blockId replicated to ${peersReplicatedTo.mkString(", ")}")
-    return true
+    true
   }
 
   /**

core/src/main/scala/org/apache/spark/storage/BlockManagerDecommissioner.scala

@@ -345,7 +345,7 @@ private[storage] class BlockManagerDecommissioner(
         s"process: ${blocksFailedReplication.mkString(",")}")
       return true
     }
-    return false
+    false
   }
 
   private def migrateBlock(blockToReplicate: ReplicateBlock): Boolean = {

core/src/main/scala/org/apache/spark/util/SizeEstimator.scala

@@ -156,7 +156,7 @@ object SizeEstimator extends Logging {
         val guess = Runtime.getRuntime.maxMemory < (32L*1024*1024*1024)
         val guessInWords = if (guess) "yes" else "not"
         logWarning("Failed to check whether UseCompressedOops is set; assuming " + guessInWords)
-        return guess
+        guess
     }
   }
 

repl/src/main/scala/org/apache/spark/repl/ExecutorClassLoader.scala

@@ -213,7 +213,7 @@ class ExecutorClassLoader(
         ClassWriter.COMPUTE_FRAMES + ClassWriter.COMPUTE_MAXS)
       val cleaner = new ConstructorCleaner(name, cw)
       cr.accept(cleaner, 0)
-      return cw.toByteArray
+      cw.toByteArray
     } else {
       // Pass the class through unmodified
       val bos = new ByteArrayOutputStream
@@ -227,7 +227,7 @@ class ExecutorClassLoader(
           done = true
         }
       }
-      return bos.toByteArray
+      bos.toByteArray
     }
   }
 
@@ -257,9 +257,9 @@ extends ClassVisitor(ASM9, cv) {
       mv.visitInsn(RETURN)
       mv.visitMaxs(-1, -1) // stack size and local vars will be auto-computed
       mv.visitEnd()
-      return null
+      null
     } else {
-      return mv
+      mv
     }
   }
 }