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

We exclude testData pattern from copyright scope

analysis/low-level-api-fir/testData/getOrBuildFir/calls/callArgument.txt

@@ -0,0 +1,14 @@
+KT element: KtValueArgument
+FIR element: FirConstExpressionImpl
+FIR source kind: KtRealSourceElementKind
+
+FIR element rendered:
+Int(1)
+
+FIR FILE:
+FILE: [ResolvedTo(IMPORTS)] callArgument.kt
+    public final [ResolvedTo(CONTRACTS)] fun y([ResolvedTo(CONTRACTS)] a: R|kotlin/Int|): R|kotlin/Unit| {
+    }
+    public final [ResolvedTo(BODY_RESOLVE)] fun x(): R|kotlin/Unit| {
+        R|/y|(Int(1))
+    }