Guard e2e tun and udp channels on close #1436

Job	Run time
Build all and test on ubuntu-linux	2m 8s
Build all and test on ubuntu-linux	1m 58s
Build all and test on ubuntu-linux	2m 2s
Build all and test on ubuntu-linux	1m 49s
Build all and test on ubuntu-linux	1m 50s
Build and test on linux with boringcrypto	2m 13s
Build and test on linux with boringcrypto	2m 14s
Build and test on linux with boringcrypto	2m 7s
Build and test on linux with boringcrypto	2m 6s
Build and test on linux with boringcrypto	2m 7s
Build and test on windows-latest	3m 32s
Build and test on windows-latest	3m 3s
Build and test on windows-latest	3m 11s
Build and test on windows-latest	3m 18s
Build and test on windows-latest	5m 48s
Build and test on macos-11	2m 52s
Build and test on macos-11	6m 23s
Build and test on macos-11	2m 17s
Build and test on macos-11	2m 21s
Build and test on macos-11	2m 25s
	55m 44s

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