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

We exclude testData pattern from copyright scope

analysis/low-level-api-fir/testData/inBlockModification/rawContractScript.kts

@@ -0,0 +1,9 @@
+fun foo(arg: Any?, num: Int?, block: () -> Unit) contract [
+    returns() implies (arg is String),
+    returns() implies (num != null),
+    callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+] {
+    require(arg is String)
+    require(num != null)
+    <expr>block</expr>()
+}