JVM_IR KT-34594 strip fake variable initialization during inlining

compiler/testData/codegen/bytecodeText/inline/noFakeVariableForInlineOnlyFun.kt

@@ -1,17 +1,23 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+
 @Suppress("INVISIBLE_REFERENCE", "INVISIBLE_MEMBER")
 @kotlin.internal.InlineOnly
-inline fun inlineOnlyFun() = 42
+inline fun inlineOnlyFun(): Int {
+    var unused = 0
+    var used1 = 0
+    var used2 = 0
+    ++used2
+    return 42 + used1
+}
 
 fun test() = inlineOnlyFun()
 
 // JVM_TEMPLATES
 // 1 LDC 0
-// 1 ICONST_0
-// 0 ISTORE 1
-// 2 ISTORE 0
+// 5 ICONST_0
+// 6 ISTORE
 
 // JVM_IR_TEMPLATES
 // 0 LDC 0
-// 0 ICONST_0
-// 0 ISTORE 1
-// 0 ISTORE 0
+// 5 ICONST_0
+// 5 ISTORE