[LL FIR] rename testdata to testData to avoid copyright generation

We exclude testData pattern from copyright scope

analysis/low-level-api-fir/testData/nonLocalDeclarationAnchors/localFunctionInsideStringTemplate.kt

@@ -0,0 +1,9 @@
+package one
+
+open class ClassWithParameter(s: String)
+
+class TopLevelClass : ClassWithParameter("${
+    fun(): String {
+        return ""
+    }()
+}")