[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/setOperatorScript.kts

@@ -0,0 +1,10 @@
+package test
+
+class B(val n: Int) {
+    operator fun set(i: Int, a: B) {}
+    operator fun get(i: Int) : B {}
+    operator fun inc() : B {}
+}
+
+var a = B(1)
+<expr>a[2]</expr>++