[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/forExpressionRangeScript.kts

@@ -0,0 +1,6 @@
+// LOOK_UP_FOR_ELEMENT_OF_TYPE: org.jetbrains.kotlin.psi.KtBinaryExpression
+fun foo() {
+    for (x in <expr>0..1</expr>) {
+
+    }
+}