Flaky test: TestCloseWhileWriting, TestCloseWhileReading

[thaJeztah]

Description

• tests were added in ssh: fix error on commandconn close, add ping and default timeout #4226

https://github.com/docker/cli/actions/runs/5271207127/jobs/9531750668?pr=4355

--- FAIL: TestCloseWhileWriting (0.00s)
    commandconn_unix_test.go:181: assertion failed: expected error to contain "EOF", got "write |1: file already closed"
--- FAIL: TestCloseWhileReading (0.00s)
    commandconn_unix_test.go:211: assertion failed: expected error to contain "EOF", got "read |0: file already closed"

[thaJeztah]

Also seen failing on Linux #4366 (comment)