Wait for `closeFuture` instead of close promise in `NIOAsyncChannel`'s `executeThenClose` #1122

Job	Run time
Construct integration test matrix	3s
Vsock tests	2m 5s
Benchmarks / Construct Benchmarks matrix	4s
Cxx interop / Construct Cxx interop matrix	2s
Unit tests / Construct unit test matrix	4s
Soundness / Documentation check	2m 12s
Soundness / Broken symlinks check	6s
Soundness / API breakage check	2m 3s
Soundness / Format check	46s
Soundness / License headers check	10s
Soundness / Python lint check	8s
Soundness / Shell check	35s
Soundness / Unacceptable language check	2s
Soundness / YAML lint check	3s
Integration tests / Linux (5.9)	15m 33s
Integration tests / Linux (5.10)	14m 14s
Integration tests / Linux (6.0)	16m 29s
Integration tests / Linux (nightly-6.0)	16m 29s
Integration tests / Linux (nightly-main)	16m 46s
Cxx interop / Cxx interop / Linux (5.9)	1m 11s
Cxx interop / Cxx interop / Linux (5.10)	1m 9s
Cxx interop / Cxx interop / Linux (6.0)	1m 18s
Cxx interop / Cxx interop / Linux (nightly-6.0)	1m 38s
Cxx interop / Cxx interop / Linux (nightly-main)	1m 45s
Benchmarks / Benchmarks / Linux (5.9)	5m 17s
Benchmarks / Benchmarks / Linux (5.10)	5m 0s
Benchmarks / Benchmarks / Linux (6.0)	5m 15s
Benchmarks / Benchmarks / Linux (nightly-6.0)	6m 10s
Benchmarks / Benchmarks / Linux (nightly-main)	4m 28s
Unit tests / Unit tests / Linux (5.9)	3m 45s
Unit tests / Unit tests / Linux (5.10)	3m 43s
Unit tests / Unit tests / Linux (6.0)	4m 12s
Unit tests / Unit tests / Linux (nightly-6.0)	4m 32s
Unit tests / Unit tests / Linux (nightly-main)	4m 37s
	2h 21m 54s

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