Fix SubmitWithFlush not updating MegaBuffer cycle

The `CommandExecutor`'s `MegaBuffer` was not being updated with the latest `FenceCycle` on being flushed in `SubmitWIthFlush`, this led to the megabuffer being overwritten prior to its GPU-side usage being complete. This commit fixes that by replacing the cycle to the latest cycle and prevents any races that occurred prior.

app/src/main/cpp/skyline/gpu/interconnect/command_executor.cpp

@@ -350,6 +350,7 @@ namespace skyline::gpu::interconnect {
             TRACE_EVENT("gpu", "CommandExecutor::SubmitWithFlush");
             SubmitInternal();
             cycle = activeCommandBuffer.Reset();
+            megaBuffer.ReplaceCycle(cycle);
             megaBuffer.Reset();
         }
         ResetInternal();