Python: Use InlineExpectationsTest for field-flow tests

I deleted the old tests, so it's very clear what tests to look for

Author: RasmusWL

python/ql/test/experimental/dataflow/fieldflow/allLocalFlow.expected

@@ -0,0 +1,13 @@
+import python
+import experimental.dataflow.TestUtil.FlowTest
+import experimental.dataflow.testConfig
+
+class DataFlowTest extends FlowTest {
+  DataFlowTest() { this = "DataFlowTest" }
+
+  override string flowTag() { result = "flow" }
+
+  override predicate relevantFlow(DataFlow::Node source, DataFlow::Node sink) {
+    exists(TestConfiguration cfg | cfg.hasFlow(source, sink))
+  }
+}