signal: Remove os.Kill (SIGKILL) from signal list as it cannot be caught

[mohamedawnallah]

Is your feature request related to a problem? Please describe.

Currently, the signal list includes os.Kill (which corresponds to SIGKILL), but this signal cannot be caught by the program. Since SIGKILL is a non-catchable signal used to immediately terminate processes, including it in the signal list may not have the desired effect.

lnd/signal/signal.go

Lines 132 to 137 in a388c1f

	signalsToCatch := []os.Signal{
	os.Interrupt,
	os.Kill,
	syscall.SIGTERM,
	syscall.SIGQUIT,
	}

Describe the solution you'd like

Remove os.Kill from the signal list to ensure that only catchable signals like SIGTERM,SIGQUIT, and os.Interrupt (which corresponds to SIGINT) are handled by the program.

Describe alternatives you've considered

None. Since SIGKILL cannot be caught, including it in the list seems not achieving any functional purpose. Removing it would simplify and streamline the signal handling process.

Additional context

This opportunity for improvement was noticed while working on PR #9395.