WhenWithOnlyElse: don't remove when subject variable if needed

#KT-30975 Fixed

idea/testData/inspectionsLocal/whenWithOnlyElse/subjectVariable/hasSameNameVariable2.kt

@@ -0,0 +1,12 @@
+// WITH_RUNTIME
+fun test() {
+    <caret>when (val a = 42) {
+        else -> {
+            use(a, a)
+            use(a, a)
+        }
+    }
+    val a = 33
+}
+
+fun use(i: Int, j: Int) {}