Disable the auto-update switch when auto-update is disabled

Error

When the update-check-delay option is set to 0, the auto-updater is disabled.
But in the Settings GUI, we can still change the value of the auto-update switch.

Fix

1) The switch must take into consideration the update-check-delay option, in addtition to the current checks.
2) The switch must be disabled, but still visible, if update-check-delay==0