Fix sendability issues in tests #138

Job	Run time
Cxx interop / Construct Cxx interop matrix	3s
Unit tests / Construct unit test matrix	5s
Soundness / API breakage check	4m 24s
Soundness / Documentation check	3m 17s
Soundness / Broken symlinks check	3s
Soundness / Format check	43s
Soundness / License headers check	5s
Soundness / Unacceptable language check	5s
Soundness / Python lint check	8s
Soundness / Shell check	33s
Soundness / YAML lint check	4s
Static SDK / Static SDK / Linux (latest-release Jammy)	3m 37s
Static SDK / Static SDK / Linux (main Jammy)	2m 5s
Cxx interop / Cxx interop / Linux (5.10)	2m 31s
Cxx interop / Cxx interop / Linux (6.0)	2m 58s
Cxx interop / Cxx interop / Linux (6.1)	2m 56s
Cxx interop / Cxx interop / Linux (nightly-next)	3m 37s
Cxx interop / Cxx interop / Linux (nightly-main)	3m 43s
Unit tests / Unit tests / Linux (5.10)	2m 33s
Unit tests / Unit tests / Linux (6.0)	5m 19s
Unit tests / Unit tests / Linux (6.1)	5m 1s
Unit tests / Unit tests / Linux (nightly-next)	5m 44s
Unit tests / Unit tests / Linux (nightly-main)	6m 4s
	55m 38s

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