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

We exclude testData pattern from copyright scope

analysis/low-level-api-fir/testData/getOrBuildFir/invalidCode/secondaryConstructor.kt

@@ -0,0 +1,5 @@
+annotation class JsQualifier : kotlin.Annotation {
+    public constructor JsQualifier(<expr>value</expr>: kotlin.String)
+
+    public final val value: kotlin.String { get; }
+}