[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/expectAndActualInTheSameFile.kt

@@ -0,0 +1,12 @@
+fun main() {
+    println("Hello, Kotlin/Native!")
+}
+
+expect fun f()
+
+fun test() {
+}
+
+actual fun f() { <expr>println("Hello")</expr> }
+
+