vmm: imporve observability to vmm-task & vmm-sandboxer #1250

Job	Run time
tests (vmm/sandbox, --all-features)	3m 7s
checks (vmm/sandbox, --all-features)	1m 51s
tests (vmm/task, --all-features)	2m 50s
checks (vmm/task, --all-features)	1m 54s
tests (shim, --all-features)	2m 38s
checks (shim, --all-features)	1m 56s
tests (quark, --all-features)	2m 30s
checks (quark, --all-features)	1m 56s
tests (runc, --all-features)	3m 2s
checks (runc, --all-features)	1m 38s
tests (wasm, --features=wasmedge, 0.13.5)	3m 6s
checks (wasm, --features=wasmedge, 0.13.5)	1m 42s
tests (wasm, --features=wasmtime)	3m 7s
checks (wasm, --features="wasmedge, wasmedge_wasi_nn", 0.13.5)	1m 49s
checks (wasm, --features=wasmtime)	1m 46s
	34m 52s

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