Escape special names with backticks in test data

#KT-51248

compiler/testData/loadJava/compiledKotlin/prop/ExtValIntTInClass.txt

@@ -3,5 +3,5 @@ package test
 public final class ExtValInClass</*0*/ T> {
     /*primary*/ public constructor ExtValInClass</*0*/ T>()
     public final val kotlin.Int.asas: T
-        public final fun kotlin.Int.<get-asas>(): T
+        public final fun kotlin.Int.`<get-asas>`(): T
 }