integration-cli: TestSlowStdinClosing: add logs, and potential naming conflict

This test has become quite flaky on Windows / Windows with Containerd.

Looking at the test, I noticed that it's running a test three times (according
to the comment "as it failed ~ 50% of the time"). However;

- it uses the `--rm` option to clean up the container after it terminated
- it uses a fixed name for the containers that are started

I had a quick look at the issue that it was created for, and neither of those
options were mentioned in the reported bug (so are just part of the test setup).

I think the test was written when the `--rm` option was still client-side, in which
case the cli would not terminate until it removed the container (making the
remove synchronous). Current versions of docker have moved the `--rm` to the
daemon side, and (if I'm not mistaken) performed asynchronous, and therefore could
potentially cause a conflicting name.

This patch:

- removes the fixed name (the test doesn't require the container to have a
  specific name, so we can just use a random name)
- adds logs to capture the stderr and stdout output of the run (so that we're
  able to capture failure messages).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

integration-cli/docker_cli_run_test.go

@@ -4157,17 +4157,19 @@ func (s *DockerSuite) TestRunEmptyEnv(c *testing.T) {
 
 // #28658
 func (s *DockerSuite) TestSlowStdinClosing(c *testing.T) {
-	name := "testslowstdinclosing"
-	repeat := 3 // regression happened 50% of the time
+	const repeat = 3 // regression happened 50% of the time
 	for i := 0; i < repeat; i++ {
 		cmd := icmd.Cmd{
-			Command: []string{dockerBinary, "run", "--rm", "--name", name, "-i", "busybox", "cat"},
+			Command: []string{dockerBinary, "run", "--rm", "-i", "busybox", "cat"},
 			Stdin:   &delayedReader{},
 		}
 		done := make(chan error, 1)
 		go func() {
-			err := icmd.RunCmd(cmd).Error
-			done <- err
+			result := icmd.RunCmd(cmd)
+			if out := result.Combined(); out != "" {
+				c.Log(out)
+			}
+			done <- result.Error
 		}()
 
 		select {