KT-5248 Don't wrap variable if it is captured only in inlined closures

Remove non-escaping Ref's on bytecode postprocessing pass.

compiler/testData/codegen/box/closures/capturedVarsOptimization/sharedSlotsWithCapturedVars.kt

@@ -0,0 +1,19 @@
+// WITH_RUNTIME
+
+fun box(): String {
+    run {
+        run {
+            var x = 0
+            run { ++x }
+            if (x == 0) return "fail"
+        }
+
+        run {
+            var x = 0
+            run { x++ }
+            if (x == 0) return "fail"
+        }
+    }
+
+    return "OK"
+}