Fixes audio crash and issues w/ audio playback (#1633)

This was caused by the main thread audio update not being called all the
time, especially Editor Game mode.

The crash was due to main thread containers not being processed and
emptied of their requests.

Signed-off-by: amzn-phist <52085794+amzn-phist@users.noreply.github.com>

Code/CryEngine/CryCommon/ISystem.h

@@ -807,11 +807,6 @@ struct ISystem
     //   Updates only require components during loading
     virtual bool UpdateLoadtime() = 0;
 
-    // Summary:
-    //   Optimisation: do part of the update while waiting for occlusion queries to complete
-    virtual void DoWorkDuringOcclusionChecks() = 0;
-    virtual bool NeedDoWorkDuringOcclusionChecks() = 0;
-
     // Summary:
     //   Retrieve the name of the user currently logged in to the computer.
     virtual const char* GetUserName() = 0;

Code/CryEngine/CryCommon/Mocks/ISystemMock.h

@@ -26,10 +26,6 @@ public:
         bool(int, int));
     MOCK_METHOD0(UpdateLoadtime,
         bool());
-    MOCK_METHOD0(DoWorkDuringOcclusionChecks,
-        void());
-    MOCK_METHOD0(NeedDoWorkDuringOcclusionChecks,
-        bool());
     MOCK_METHOD0(RenderStatistics,
         void());
     MOCK_METHOD0(GetUserName,