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

We exclude testData pattern from copyright scope

analysis/low-level-api-fir/testData/classId/localClassInsideLambdaCallInsideStringTemplate.kt

@@ -0,0 +1,10 @@
+package one
+
+/* ClassId: one/ClassWithParameter */open class ClassWithParameter(s: String)
+
+/* ClassId: one/TopLevelClass */class TopLevelClass : ClassWithParameter("${
+    {
+        /* ClassId: null */class F
+        F()
+    }()
+}")