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

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

tests/unit/rpc/RPCHelpersTests.cpp

@@ -86,16 +86,10 @@ constexpr auto kAMM_ID = 54321;
 }  // namespace
 
 class RPCHelpersTest : public util::prometheus::WithPrometheus, public MockBackendTest, public SyncAsioContextTest {
-    void
-    SetUp() override
+public:
+    RPCHelpersTest()
     {
         backend_->setRange(10, 300);
-        SyncAsioContextTest::SetUp();
-    }
-    void
-    TearDown() override
-    {
-        SyncAsioContextTest::TearDown();
     }
 
 protected:

tests/unit/rpc/handlers/GetAggregatePriceTests.cpp

@@ -89,10 +89,8 @@ mockLedgerObject(
 
 class RPCGetAggregatePriceHandlerTest : public HandlerBaseTest {
 protected:
-    void
-    SetUp() override
+    RPCGetAggregatePriceHandlerTest()
     {
-        HandlerBaseTest::SetUp();
         backend_->setRange(kRANGE_MIN, kRANGE_MAX);
     }
 };

tests/unit/rpc/handlers/ServerInfoTests.cpp

@@ -56,24 +56,11 @@ constexpr auto kCLIENT_IP = "1.1.1.1";
 }  // namespace
 
 struct RPCServerInfoHandlerTest : HandlerBaseTest, MockLoadBalancerTest, MockCountersTest {
-    void
-    SetUp() override
+    RPCServerInfoHandlerTest()
     {
-        HandlerBaseTest::SetUp();
-        MockLoadBalancerTest::SetUp();
-        MockCountersTest::SetUp();
-
         backend_->setRange(10, 30);
     }
 
-    void
-    TearDown() override
-    {
-        MockCountersTest::TearDown();
-        MockLoadBalancerTest::TearDown();
-        HandlerBaseTest::TearDown();
-    }
-
     static void
     validateNormalOutput(rpc::ReturnType const& output)
     {