[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/binaryExpressionOperator.txt

@@ -0,0 +1,11 @@
+KT element: KtOperationReferenceExpression
+FIR element: FirResolvedNamedReferenceImpl
+FIR source kind: KtRealSourceElementKind
+
+FIR element rendered:
+R|kotlin/Int.plus|
+
+FIR FILE:
+FILE: [ResolvedTo(IMPORTS)] binaryExpressionOperator.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|