add tests for system shutdown #2415

Job	Run time
build	2m 30s
test-fast (tests/Proto.Actor.Tests/*.csproj)	1m 44s
test-slow (net7.0, tests/Proto.Cluster.Tests/*.csproj)	7m 44s
test-fast (tests/Proto.Remote.Tests/*.csproj)	2m 48s
test-slow (net7.0, tests/Proto.Cluster.PartitionIdentity.Tests/*.csproj)	4m 15s
test-fast (tests/Proto.OpenTelemetry.Tests/*.csproj)	1m 24s
test-slow (net7.0, tests/Proto.Cluster.RedisIdentity.Tests/*.csproj)	2m 53s
test-fast (tests/Proto.Cluster.CodeGen.Tests/*.csproj)	57s
test-slow (net7.0, tests/Proto.Cluster.PubSub.Tests/*.csproj)	3m 20s
test-slow (net6.0, tests/Proto.Cluster.Tests/*.csproj)	7m 42s
test-slow (net6.0, tests/Proto.Cluster.PartitionIdentity.Tests/*.csproj)	2m 47s
test-slow (net6.0, tests/Proto.Cluster.RedisIdentity.Tests/*.csproj)	2m 55s
test-slow (net6.0, tests/Proto.Cluster.PubSub.Tests/*.csproj)	3m 35s
	44m 34s

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