Ensure to invoke the Busybox `passwd` applet to change the system password in a non-interactive manner. Non-Busybox variants may not take the new password input from stdin or use password hashes which are not supported by musl's `crypt()` implementation by default. Fixes: #5629 Signed-off-by: Jo-Philipp Wich <jo@mein.io> (cherry picked from commit 22e2bfb09667e167a93b5eca4487ac41669126d9)