vmm: imporve observability to vmm-task & vmm-sandboxer #1310

Job	Run time
tests (vmm/sandbox, --all-features)	3m 46s
tests (vmm/task, --all-features)	3m 5s
checks (vmm/sandbox, --all-features)	4m 44s
tests (shim, --all-features)	2m 35s
checks (vmm/task, --all-features)	4m 13s
checks (shim, --all-features)	3m 59s
tests (quark, --all-features)	2m 32s
checks (quark, --all-features)	3m 58s
tests (runc, --all-features)	3m 12s
tests (wasm, --features=wasmedge, 0.13.5)	3m 18s
tests (wasm, --features=wasmtime)	3m 44s
checks (runc, --all-features)	4m 16s
checks (wasm, --features=wasmedge, 0.13.5)	4m 41s
checks (wasm, --features="wasmedge, wasmedge_wasi_nn", 0.13.5)	4m 43s
checks (wasm, --features=wasmtime)	4m 47s
	57m 33s

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