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

We exclude testData pattern from copyright scope

analysis/low-level-api-fir/testData/getOrBuildFir/expressions/throwExpression.txt

@@ -0,0 +1,12 @@
+KT element: KtThrowExpression
+FIR element: FirThrowExpressionImpl
+FIR source kind: KtRealSourceElementKind
+
+FIR element rendered:
+throw R|java/lang/IllegalStateException.IllegalStateException|()
+
+FIR FILE:
+FILE: [ResolvedTo(IMPORTS)] throwExpression.kt
+    public final [ResolvedTo(BODY_RESOLVE)] fun x(): R|kotlin/Unit| {
+        throw R|java/lang/IllegalStateException.IllegalStateException|()
+    }