Ignore prompt if stdin not a tty on machine start

[baude]

When starting a machine and the user has not explicitly passed -u=true|false AND stdin is a not a tty, we should not prompt to update connections.

Fixes: #27556

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[Luap99]

btw I think we can add a test for this.
The tests do expose setStdin() so we could set it to a buffer and then after the command runs make sure the buffer was not read.

[packit-as-a-service]

[NON-BLOCKING] Packit jobs failed. @containers/packit-build please check. Everyone else, feel free to ignore.

[Honny1]

LGTM, once @Luap99's comments have been addressed.

[baude]

btw I think we can add a test for this. The tests do expose setStdin() so we could set it to a buffer and then after the command runs make sure the buffer was not read.

When I did this, the buffer is still being read. I could not pinpoint why (in short order). But the code path is correct and it's going through the right conditionals. So we check the output for the usual prompting message to ensure it is not present.

[TomSweeneyRedHat]

nit of a nit to be cleaned if you have to repush

Suggested change

	// This might be kind of lame but when using the command, but if you don't
	// This might be kind of lame but when using the command, if you don't

[TomSweeneyRedHat]

LGTM once tests and @Luap99 are hip.