partial revert 54cd5fb8eb (#4355)

- [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.

-------------------
It fixes display issues when the overlay applet is enabled, thanks Bruno.

Fixes freezes when enabling real applet keyboard  in qlaunch.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4355
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Reviewed-by: lizzie <lizzie@eden-emu.dev>
Reviewed-by: Maufeat <sahyno1996@gmail.com>

src/core/hle/service/am/display_layer_manager.cpp

@@ -73,20 +73,16 @@ Result DisplayLayerManager::CreateManagedDisplayLayer(u64* out_layer_id) {
     R_TRY(m_manager_display_service->CreateManagedLayer(
         out_layer_id, 0, display_id, Service::AppletResourceUserId{m_process->GetProcessId()}));
 
-    m_manager_display_service->SetLayerVisibility(m_visible, *out_layer_id);
-    (void)m_display_service->GetContainer()->SetLayerStackMask(*out_layer_id,
-                                                              this->GetLayerStackMask());
-
     if (m_applet_id != AppletId::Application) {
         (void)m_manager_display_service->SetLayerBlending(m_blending_enabled, *out_layer_id);
         if (m_applet_id == AppletId::OverlayDisplay) {
-            (void)m_manager_display_service->SetLayerZIndex(Overlay, *out_layer_id);
+            (void)m_manager_display_service->SetLayerZIndex(-1, *out_layer_id);
             (void)m_display_service->GetContainer()->SetLayerIsOverlay(*out_layer_id, true);
         } else {
-            (void)m_manager_display_service->SetLayerZIndex(Foreground, *out_layer_id);
+            (void)m_manager_display_service->SetLayerZIndex(1, *out_layer_id);
         }
     }
-
+    (void)m_display_service->GetContainer()->SetLayerZIndex(*out_layer_id, true);
     m_managed_display_layers.emplace(*out_layer_id);
 
     R_SUCCEED();
@@ -126,12 +122,11 @@ Result DisplayLayerManager::IsSystemBufferSharingEnabled() {
 
     // Ensure the overlay layer is visible
     m_manager_display_service->SetLayerVisibility(m_visible, m_system_shared_layer_id);
-    (void)m_display_service->GetContainer()->SetLayerStackMask(m_system_shared_layer_id,
-                                                              this->GetLayerStackMask());
     m_manager_display_service->SetLayerBlending(m_blending_enabled, m_system_shared_layer_id);
-    s32 initial_z = Foreground;
+    s32 initial_z = 1;
+    (void)m_display_service->GetContainer()->SetLayerZIndex(m_system_shared_layer_id, true);
     if (m_applet_id == AppletId::OverlayDisplay) {
-        initial_z = Overlay;
+        initial_z = -1;
         (void)m_display_service->GetContainer()->SetLayerIsOverlay(m_system_shared_layer_id, true);
     }
     m_manager_display_service->SetLayerZIndex(initial_z, m_system_shared_layer_id);

src/core/hle/service/vi/shared_buffer_manager.cpp

@@ -300,28 +300,6 @@ Result SharedBufferManager::CreateSession(Kernel::KProcess* owner_process, u64*
             }
         }
 
-        // Claim a presentation slot range.
-        u32 slot_base = 0;
-
-        std::array<bool, SharedBufferMaxSessions> in_use{};
-        for (const auto& [existing_aruid, existing] : m_sessions) {
-            const u32 index = existing.presentation_slot_base / SharedBufferSlotsPerSession;
-
-            if (index < in_use.size())
-                in_use[index] = true;
-        }
-
-        u32 index = 0;
-        while (index < in_use.size() && in_use[index])
-            index++;
-
-        if (index >= in_use.size()) {
-            LOG_ERROR(Service_VI, "Out of shared buffer presentation slots ({} sessions)", SharedBufferMaxSessions);
-            R_THROW(VI::ResultOperationFailed);
-        }
-
-        slot_base = index * SharedBufferSlotsPerSession;
-
         // Map into process.
         Common::ProcessAddress map_address{};
         R_TRY(MapSharedBufferIntoProcessAddressSpace(std::addressof(map_address), m_buffer_page_group,
@@ -330,7 +308,6 @@ Result SharedBufferManager::CreateSession(Kernel::KProcess* owner_process, u64*
         // Create new session.
         auto [it, was_emplaced] = m_sessions.emplace(aruid, SharedBufferSession{});
         auto& session = it->second;
-        session.presentation_slot_base = slot_base;
 
         auto& container = m_nvdrv->GetContainer();
         session.session_id = container.OpenSession(owner_process);