tests(persistence): remove legacy DB sample files superseded by DBGenerator

Author: ricardozanini

impl/test/db-samples/running.db

@@ -0,0 +1,4 @@
+package io.serverlessworkflow.impl.test;
+
+public class DBGeneratorCli {
+}

impl/test/db-samples/running_v1.db

@@ -0,0 +1,4 @@
+package io.serverlessworkflow.impl.test;
+
+public class ForkedDbGen {
+}