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

We exclude testData pattern from copyright scope

analysis/low-level-api-fir/testData/fileBasedDeclarationProvider/local.kt

@@ -0,0 +1,12 @@
+// FUNCTION: test/#foo
+
+package test
+
+fun foo() {
+    fun bar() {
+        fun baz() {
+            class Foo
+            object Bar
+        }
+    }
+}