[JVM_IR, IR] Remove more needless temporary variables.

Avoid using a separate origin for temporary variables introduced
for for loops. That doesn't add anything and gives one more case
for optimizations to deal with.

Extend the JVM specific optimizations to remove temporary
variables to deal with more cases encountered in for loops
lowering.

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/HeaderProcessor.kt

@@ -310,8 +310,7 @@ internal class HeaderProcessor(
                         progressionType.elementCastFunctionName
                     ),
                     nameHint = "inductionVariable",
-                    isMutable = true,
-                    origin = IrDeclarationOrigin.FOR_LOOP_IMPLICIT_VARIABLE
+                    isMutable = true
                 )
 
                 // Due to features of PSI2IR we can obtain nullable arguments here while actually
@@ -325,8 +324,7 @@ internal class HeaderProcessor(
                             progressionType.elementCastFunctionName
                         )
                     ),
-                    nameHint = "last",
-                    origin = IrDeclarationOrigin.FOR_LOOP_IMPLICIT_VARIABLE
+                    nameHint = "last"
                 )
 
                 val stepValue = scope.createTemporaryVariable(
@@ -336,8 +334,7 @@ internal class HeaderProcessor(
                             progressionType.stepCastFunctionName
                         )
                     ),
-                    nameHint = "step",
-                    origin = IrDeclarationOrigin.FOR_LOOP_IMPLICIT_VARIABLE
+                    nameHint = "step"
                 )
 
                 return when (headerInfo) {

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/ProgressionHandlers.kt

@@ -351,8 +351,7 @@ internal abstract class IndexedGetIterationHandler(protected val context: Common
             // This also ensures that the semantics of re-assignment of array variables used in the loop is consistent with the semantics
             // proposed in https://youtrack.jetbrains.com/issue/KT-21354.
             val arrayReference = scope.createTemporaryVariable(
-                expression, nameHint = "indexedObject",
-                origin = IrDeclarationOrigin.FOR_LOOP_IMPLICIT_VARIABLE
+                expression, nameHint = "indexedObject"
             )
 
             val last = irCall(expression.type.sizePropertyGetter).apply {