Moves the logic up a level to the panel_ctrl. This cleans up the code
and makes the lazy loading available for all panels.

Removes the config option and making this default behavior. We can
add back the config option if we get feedback that it is needed during
the beta phase of the v4.3.0 release.

Unbind the scroll handler on panel destroy to avoid memory leaks.

Fix for png rendering, it did not match all forms of dashboard-solo.
e.g. /render/dashboard-solo/db...

Fix for when taking a snapshot. All the panels get refreshed then
even the panels that are not visible.

Closes #5216.