net: TestTCPSupriousConnSetupCompletion is flaky

[josharian]

Broken out from #17472.

$ go test -run=TestTCPSupriousConnSetupCompletion net
ok  	net	3.614s
$ go test -run=TestTCPSupriousConnSetupCompletion net
--- FAIL: TestTCPSupriousConnSetupCompletion (22.69s)
	tcpsock_unix_test.go:60: #6589: dial tcp 127.0.0.1:55916: context deadline exceeded
	tcpsock_unix_test.go:60: #6732: dial tcp 127.0.0.1:55916: context deadline exceeded
	tcpsock_unix_test.go:60: #6786: dial tcp 127.0.0.1:55916: context deadline exceeded
	tcpsock_unix_test.go:60: #6830: dial tcp 127.0.0.1:55916: context deadline exceeded
FAIL
FAIL	net	22.765s

Also, please fix the spelling error in the test name.

[gopherbot]

CL https://golang.org/cl/33149 mentions this issue.