vmm: imporve observability to vmm-task & vmm-sandboxer #1298

Job	Run time
tests (vmm/sandbox, --all-features)	3m 51s
checks (vmm/sandbox, --all-features)	4m 46s
tests (vmm/task, --all-features)	2m 59s
checks (vmm/task, --all-features)	4m 4s
tests (shim, --all-features)	2m 40s
checks (shim, --all-features)	4m 0s
tests (quark, --all-features)	2m 32s
checks (quark, --all-features)	3m 52s
tests (runc, --all-features)	3m 3s
checks (runc, --all-features)	4m 33s
tests (wasm, --features=wasmedge, 0.13.5)	3m 22s
checks (wasm, --features=wasmedge, 0.13.5)	4m 40s
tests (wasm, --features=wasmtime)	3m 48s
checks (wasm, --features="wasmedge, wasmedge_wasi_nn", 0.13.5)	4m 39s
checks (wasm, --features=wasmtime)	4m 44s
	57m 33s

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