Escape special names with backticks in test data

#KT-51248

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

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