fix(userspace/libsinsp/test): avoid deadlocks in mpsc queue tests #4967

Job	Run time
build-libs-linux-amd64 😁 (system_deps)	5m 16s
build-libs-linux-amd64 😁 (bundled_deps)	16m 35s
build-libs-linux-amd64-asan 🧐	8m 33s
build-shared-libs-linux-amd64 🧐	3m 35s
build-libs-linux-amd64 😁 (system_deps_w_chisels)	5m 22s
build-libs-linux-amd64-static 🎃	22m 41s
build-libs-linux-amd64 😁 (system_deps_minimal)	3m 39s
build-libs-linux-arm64 😁 (system_deps)	5m 19s
build-libs-linux-arm64 😁 (bundled_deps)	16m 53s
build-libs-linux-arm64 😁 (system_deps_w_chisels)	5m 30s
build-libs-emscripten 🧐	3m 54s
build-libs-linux-arm64 😁 (system_deps_minimal)	3m 54s
build-libs-others-amd64 😨 (windows-latest)	6m 24s
build-shared-libs-macos-amd64 😨	3m 31s
build-libs-others-amd64 😨 (macos-latest)	10m 9s
run-e2e-tests-amd64 (system_deps)	8m 29s
test-libs-static (bundled_deps)	15m 49s
run-e2e-tests-amd64 (bundled_deps)	20m 6s
run-e2e-tests-amd64 (system_deps_w_chisels)	8m 47s
run-e2e-tests-amd64 (asan)	21m 39s
	3h 16m 5s

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