Clean up sendability in the bootstraps #1160

Job	Run time
Construct integration test matrix	5s
Vsock tests	2m 15s
Benchmarks / Construct Benchmarks matrix	3s
Cxx interop / Construct Cxx interop matrix	4s
Unit tests / Construct unit test matrix	4s
Soundness / API breakage check	2m 7s
Soundness / Broken symlinks check	3s
Soundness / Documentation check	2m 11s
Soundness / Format check	49s
Soundness / License headers check	9s
Soundness / Shell check	33s
Soundness / Unacceptable language check	3s
Soundness / Python lint check	7s
Soundness / YAML lint check	4s
Integration tests / Linux (5.9)	13m 52s
Integration tests / Linux (5.10)	13m 50s
Integration tests / Linux (6.0)	13m 51s
Integration tests / Linux (nightly-6.0)	13m 50s
Integration tests / Linux (nightly-main)	13m 50s
Cxx interop / Cxx interop / Linux (5.9)	1m 8s
Cxx interop / Cxx interop / Linux (5.10)	1m 6s
Cxx interop / Cxx interop / Linux (6.0)	1m 15s
Cxx interop / Cxx interop / Linux (nightly-6.0)	1m 29s
Cxx interop / Cxx interop / Linux (nightly-main)	1m 31s
Benchmarks / Benchmarks / Linux (5.9)	5m 10s
Benchmarks / Benchmarks / Linux (5.10)	5m 0s
Benchmarks / Benchmarks / Linux (6.0)	5m 7s
Benchmarks / Benchmarks / Linux (nightly-6.0)	6m 23s
Benchmarks / Benchmarks / Linux (nightly-main)	4m 15s
Unit tests / Unit tests / Linux (5.9)	3m 57s
Unit tests / Unit tests / Linux (5.10)	3m 48s
Unit tests / Unit tests / Linux (6.0)	4m 7s
Unit tests / Unit tests / Linux (nightly-6.0)	4m 34s
Unit tests / Unit tests / Linux (nightly-main)	4m 20s
	2h 11m 0s

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