Fixed Multiplayer unit tests.

The multiplayer unit tests created a SpawnableSystemComponent without an application to provide the Serialize Context. This caused an assert which failed the unit tests. Since the entity spawning system doesn't seem to be directly used the component was removed.

Gems/Multiplayer/Code/Tests/MultiplayerSystemTests.cpp

@@ -30,7 +30,6 @@ namespace UnitTest
         {
             SetupAllocator();
             AZ::NameDictionary::Create();
-            m_spawnableComponent = new AzFramework::SpawnableSystemComponent();
             m_netComponent = new AzNetworking::NetworkingSystemComponent();
             m_mpComponent = new Multiplayer::MultiplayerSystemComponent();
 
@@ -46,7 +45,6 @@ namespace UnitTest
         {
             delete m_mpComponent;
             delete m_netComponent;
-            delete m_spawnableComponent;
             AZ::NameDictionary::Destroy();
             TeardownAllocator();
         }
@@ -76,7 +74,6 @@ namespace UnitTest
 
         AzNetworking::NetworkingSystemComponent* m_netComponent = nullptr;
         Multiplayer::MultiplayerSystemComponent* m_mpComponent = nullptr;
-        AzFramework::SpawnableSystemComponent* m_spawnableComponent = nullptr;
     };
 
     TEST_F(MultiplayerSystemTests, TestInitEvent)