Tests: unmute debugging tests for FIR+JVM_IR

The differences between K1 and K2 are pretty unimportant in these tests.

compiler/testData/debug/localVariables/assignment.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND_K2: JVM_IR
+
 
 // FILE: test.kt
 fun box(): String {
@@ -15,7 +15,11 @@ fun box(): String {
 
 // EXPECTATIONS JVM_IR
 // test.kt:8 box:
+// EXPECTATIONS ClassicFrontend JVM_IR
 // test.kt:6 box:
+// EXPECTATIONS FIR JVM_IR
+// test.kt:5 box:
+// EXPECTATIONS JVM_IR
 // test.kt:11 box: o:java.lang.String="O":java.lang.String
 // test.kt:13 box: o:java.lang.String="O":java.lang.String, k:java.lang.String="K":java.lang.String