vulkan: don't periodically clean up render pass objects.

It's not needed.

src/modules/graphics/vulkan/Graphics.cpp

@@ -2224,8 +2224,6 @@ VkRenderPass Graphics::getRenderPass(RenderPassConfiguration &configuration)
 		renderPasses[configuration] = renderPass;
 	}
 
-	renderPassUsages[renderPass] = true;
-
 	return renderPass;
 }
 
@@ -2643,7 +2641,6 @@ static void eraseUnusedObjects(
 
 void Graphics::cleanupUnusedObjects()
 {
-	eraseUnusedObjects(renderPasses, renderPassUsages, vkDestroyRenderPass, device);
 	eraseUnusedObjects(framebuffers, framebufferUsages, vkDestroyFramebuffer, device);
 }
 

src/modules/graphics/vulkan/Graphics.h

@@ -372,7 +372,6 @@ private:
 	VkPipelineCache pipelineCache = VK_NULL_HANDLE;
 	std::unordered_map<RenderPassConfiguration, VkRenderPass, RenderPassConfigurationHasher> renderPasses;
 	std::unordered_map<FramebufferConfiguration, VkFramebuffer, FramebufferConfigurationHasher> framebuffers;
-	std::unordered_map<VkRenderPass, bool> renderPassUsages;
 	std::unordered_map<VkFramebuffer, bool> framebufferUsages;
 	std::unordered_map<uint64, VkSampler> samplers;
 	VkCommandPool commandPool = VK_NULL_HANDLE;