Remove pressDelay from image viewer flickable

Seems to create a bug where the user can accidentally scroll the
timeline behind the popup instead of the image viewer flickable itself

TODO.md

@@ -5,7 +5,6 @@
     - hflickable support kinetic scrolling disabler and speed/decel settings
     - buttons (include a working GIF play/pause)
     - keyboard controls
-    - prevent drag-scrolling timeline when image opened
 
 - clipboard preview doesn't update when copied image changes until second time
 - Avatar tooltip can get displayed in front of presence menu

src/gui/Popups/ImageViewerPopup.qml

@@ -68,7 +68,6 @@ HPopup {
 
     HFlickable {
         id: flickable
-        pressDelay: 30
         implicitWidth: window.width
         implicitHeight: window.height
         contentWidth: