JVM IR: recover accidentally lost backingField (KT-49998)

compiler/testData/codegen/bytecodeText/annotationDefaultValueOfUnsigned.kt

@@ -0,0 +1,11 @@
+// TARGET_BACKEND: JVM_IR
+
+annotation class Ann1(val value: UByte = 41u)
+annotation class Ann2(val value: UShort = 42u)
+annotation class Ann3(val value: UInt = 43u)
+annotation class Ann4(val value: ULong = 44u)
+
+// 1 default=\(byte\)41
+// 1 default=\(short\)42
+// 1 default=43
+// 1 default=44L