Optimize more redundant kotlin/jvm/internal/Refs

The number of initializations of the `value` field before the live range
begins does not really matter so long as we insert a write of a default
value to the local if there were none.

compiler/testData/codegen/bytecodeText/capturedVarsOptimization/withStackNormalization.kt

@@ -1,6 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
-// TODO KT-36648 Captured variables not optimized in JVM_IR
-
 fun add(x: Int, y: Int) = x + y
 
 fun test() {