Dota2 unreasonable use for pipeline caches

[WenqingLiAMD]

Your system information

• Steam client version (build number or date): latest
• Distribution (e.g. Ubuntu): Ubuntu 20.04.2 with AMDVLK driver
• Have you verified the game files?: [Yes]

Please describe your issue in as much detail as possible:

Dota2 creates 29 identical pipeline caches

Steps for reproducing this issue:

1. Set up ubuntu 20.04.2 system
2. Install steam and dota2, make sure the pre-caching is enabled in steam settings
3. Install AMDVLK driver from https://github.com/GPUOpen-Drivers/AMDVLK/releases/tag/v-2021.Q4.1
4. Start dota2 with -vulkan, quit, then start dota2 again, observe the memory usage

You can find dota2 creates 29 identical pipeline cache objects through the vulkan apis vkCreatePipelineCache or vkMergePipelineCaches, this kind of behavior is unreasonable.

[danginsburg]

I am working on an improvement to this using VK_EXT_pipeline_creation_cache_control.