applets/batterymonitor: don't show percentage when fully charged
When the user has opted to show the percentage on the battery icon, continuing to show it when the battery is fully charged doesn't make sense; the user knows that the battery is at either 100%, or the charge threshold they previously set. So showing them the exact number is just visual noise and can be safely omitted.
Now when you have the percentage feature turned on and the battery is fully charged and a power profile is active, you'll see this:
(It doesn't show the percentage because the battery is fully charged)