igloo: take graph sizes from the render options alone

The per-user "graph_size" profile entry was written only by the former
renderer's resize handle, so dropping the renderer left it without a
writer. Reading it too would freeze whatever size a user last dragged,
so the read goes as well and the render options become the only source.

That makes the user argument redundant, and takes four display config
fields with it that only the former renderer read.

CMK-37237

Change-Id: I7d036959b068fa160d2e39dd187a34d084732a2c