wibox.widget.systray opacity property should be hidden

[Crylia]

The opacity property should be hidden as the systray can't be transparent.

I tried it myself but I couldn't get this property to hide

This is what I've tried(tried to copy wibox.layout.flex which hides fill_space):

-- {{{ Override inherited properties we want to hide

--- From `wibox.widget.base`.
-- @property opacity
-- @tparam[opt=1.0] number opacity
-- @rangestart 0.0
-- @rangestop 1.0
-- @propertyunit A gradient between transparent (`0.0`) and opaque (`1.0`).
-- @baseclass wibox.widget.base
-- @see visible
-- @hidden

-- }}}

[actionless]

there is already open pull request for fixing that: #3664

[Crylia]

The question is now how likely is it going to be merged and when. This should be a rather easy fix (even tho I don't understand why it doesn't hide it) and would resolve some confusion that I see a lot.

At the very least one should look why this property can't be hidden (probably @Elv13)