fix #3478: abort container creation on arch detection timeout

fix #3478: abort container creation on arch detection timeout

increased the timeout for detect_arch from 5 to 10 seconds.

until now, on any error detect_architecture would fall back to amd64.
to avoid falling back due to an timeout error this function now dies
on timeout errors.

additionally minor changes to the error messages have been made.

Signed-off-by: Lorenz Stechauner <l.stechauner@proxmox.com>