[buffer_cache] Simplify GPU fence synchronization and remove GPU buffer readback (#4477)

- [x] I have read and followed the [Contribution Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/CONTRIBUTING.md#code-contributions).
- [x] I have read and followed the [AI Policy](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/AI.md)
- [x] I have read and followed the [Coding Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/Coding.md) to the best of my ability.

-------------------

This is understood to improve GPU synchronization within the buffer cache in certain edge cases.

GPU Fence Strict is no longer necessary. We now apply the stronger synchronization only in the specific case that actually requires it.

The GPU Buffer Readback has been removed, as it is no longer needed following PR #4473.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4477
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

src/video_core/renderer_vulkan/vk_buffer_cache.cpp

@@ -419,15 +419,15 @@ void BufferCacheRuntime::TickFrame(Common::SlotVector<Buffer>& slot_buffers) noe
 }
 
 u64 BufferCacheRuntime::CurrentTick() {
-    return scheduler.GetMasterSemaphore().CurrentTick();
+    return scheduler.CurrentTick();
 }
 
-u64 BufferCacheRuntime::KnownGpuTick() {
-    return scheduler.GetMasterSemaphore().KnownGpuTick();
+bool BufferCacheRuntime::IsFree(u64 tick) {
+    return scheduler.IsFree(tick);
 }
 
-void BufferCacheRuntime::Wait(u64 buffer_tick) {
-    scheduler.Wait(buffer_tick);
+void BufferCacheRuntime::Wait(u64 tick) {
+    scheduler.Wait(tick);
 }
 
 void BufferCacheRuntime::Finish() {

src/video_core/renderer_vulkan/vk_buffer_cache.h

@@ -112,9 +112,9 @@ public:
 
     u64 CurrentTick();
 
-    u64 KnownGpuTick();
+    bool IsFree(u64 tick);
 
-    void Wait(u64 buffer_tick);
+    void Wait(u64 tick);
 
     void Finish();