vmm: imporve observability to vmm-task & vmm-sandboxer #1297

Job	Run time
tests (vmm/sandbox, --all-features)	3m 47s
checks (vmm/sandbox, --all-features)	4m 47s
tests (vmm/task, --all-features)	3m 0s
checks (vmm/task, --all-features)	4m 8s
tests (shim, --all-features)	2m 37s
checks (shim, --all-features)	4m 1s
tests (quark, --all-features)	2m 36s
checks (quark, --all-features)	3m 56s
tests (runc, --all-features)	3m 7s
checks (runc, --all-features)	4m 17s
tests (wasm, --features=wasmedge, 0.13.5)	3m 19s
checks (wasm, --features=wasmedge, 0.13.5)	4m 36s
tests (wasm, --features=wasmtime)	3m 55s
checks (wasm, --features="wasmedge, wasmedge_wasi_nn", 0.13.5)	4m 35s
checks (wasm, --features=wasmtime)	4m 43s
	57m 24s

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