Change formula for font cache size

Set font cache size to one screen buffer size.
For Pixel 2 XL this increased the texture size from
3670016 to 4194304. Skia can allocate up to 4 textures
of that size.

Test: UiBenchJankTests#testInflatingEmojiListViewFling
Bug: 121157706
Change-Id: I7af1f184c6dbc10b45a8ef80a04200d518fbaa0e