* metal: fix memory leak if model is freed without any GPU operations
* metal: run dummy work only if residency sets are used
* metal: wrap function in #if defined
* metal: measure system-wide wired memory in test
* metal: always build regression test
Co-authored-by: YiChen Lv <[email protected]>
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Co-authored-by: YiChen Lv <[email protected]>