test: Remove SetUp and TearDown methods in tests (#2086)

Fix: https://github.com/XRPLF/clio/issues/910

tests/integration/data/BackendFactoryTests.cpp

@@ -85,8 +85,7 @@ protected:
 
 class BackendCassandraFactoryTestWithDB : public BackendCassandraFactoryTest {
 protected:
-    void
-    TearDown() override
+    ~BackendCassandraFactoryTestWithDB()
     {
         // drop the keyspace for next test
         data::cassandra::Handle const handle{TestGlobals::instance().backendHost};