Get NIOEmbedded clean under strict concurrency #1111

Job	Run time
Construct integration test matrix	5s
Vsock tests	2m 23s
Benchmarks / Construct Benchmarks matrix	6s
Cxx interop / Construct Cxx interop matrix	5s
Unit tests / Construct unit test matrix	3s
Soundness / API breakage check	2m 4s
Soundness / Broken symlinks check	4s
Soundness / Documentation check	2m 16s
Soundness / Format check	50s
Soundness / License headers check	8s
Soundness / Python lint check	4s
Soundness / Shell check	40s
Soundness / Unacceptable language check	3s
Soundness / YAML lint check	3s
Unit tests / Unit tests / Linux (5.9)	3m 54s
Unit tests / Unit tests / Linux (5.10)	3m 43s
Unit tests / Unit tests / Linux (6.0)	4m 5s
Unit tests / Unit tests / Linux (nightly-6.0)	4m 35s
Unit tests / Unit tests / Linux (nightly-main)	4m 44s
Integration tests / Linux (5.9)	11m 44s
Integration tests / Linux (5.10)	11m 40s
Integration tests / Linux (6.0)	11m 41s
Integration tests / Linux (nightly-6.0)	11m 41s
Integration tests / Linux (nightly-main)	11m 40s
Cxx interop / Cxx interop / Linux (5.9)	1m 16s
Cxx interop / Cxx interop / Linux (5.10)	1m 13s
Cxx interop / Cxx interop / Linux (6.0)	1m 25s
Cxx interop / Cxx interop / Linux (nightly-6.0)	1m 39s
Cxx interop / Cxx interop / Linux (nightly-main)	1m 44s
Benchmarks / Benchmarks / Linux (5.9)	5m 29s
Benchmarks / Benchmarks / Linux (5.10)	5m 1s
Benchmarks / Benchmarks / Linux (6.0)	5m 12s
Benchmarks / Benchmarks / Linux (nightly-6.0)	6m 5s
Benchmarks / Benchmarks / Linux (nightly-main)	4m 31s
	2h 1m 56s

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