Remove Animate Show Applications from the desktop (Fix "Show Applications" button)

[sergio-costas]

The "Show Applications" button fails because the Overview.ANIMATION_TIME property is now read-only (it has a "const" prefix), so it's not possible to overwrite it to show the applications list "instantaneously". It "does nothing" and shows this error in the log:

ago 28 12:20:46 raster3-PROX14-AMD gnome-shell[534248]: JS ERROR: TypeError: "ANIMATION_TIME" is read-only
                                                        _onShowAppsButtonToggled/<@file:///home/raster/.local/share/gnome-shell/extensions/dash-to-dock@micxgx.gmail.com/docking.js:2491:21
                                                        @resource:///org/gnome/shell/ui/init.js:21:20

This patch removes the option of disabling the animation, thus fixing the problem.

[3v1n0]

I think it's fine to drop this option, since it was mostly something problematic in the past, HOWEVER... Not sure if some user rely on that (but I guess no because we had no many complaints)

In case we want to keep the option, we could technically just patch Overview.animateToOverview and panel.fadeIn on click to not animate, but this looks still prone to breakage, so I think we're good dropping it.

[3v1n0]

Please, just squash your commits in one

[sergio-costas]

@3v1n0 Squashed.