applets/weather: Fix system tray detection

The applet needs to check weather it is in the system tray
to avoid showing a text label beside the icon.

As the property is a flag, it needs a bitwise operator
instead of a plain equality. This also adds a second check
(in practice both are true, but better safe than sorry)

Additionally, also hide the option completely instead of
showing it disabled, which can be confusing.
4 jobs for !272 with work/iasensio/weather-fix-systray in 3 minutes and 42 seconds (queued for 6 seconds)
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