[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/binaryExpression.txt

@@ -0,0 +1,11 @@
+KT element: KtBinaryExpression
+FIR element: FirIntegerLiteralOperatorCallImpl
+FIR source kind: KtRealSourceElementKind
+
+FIR element rendered:
+Int(1).R|kotlin/Int.plus|(Int(1))
+
+FIR FILE:
+FILE: [ResolvedTo(IMPORTS)] binaryExpression.kt
+    public final [ResolvedTo(BODY_RESOLVE)] val x: R|kotlin/Int| = Int(1).R|kotlin/Int.plus|(Int(1))
+        public [ResolvedTo(BODY_RESOLVE)] get(): R|kotlin/Int|