71406ac767 switched the IMAGE_BOMB_TOTAL_PIXELS cutoff for what
images we preview to include the number of frames in the calculation.
While accurate to the implementation (thumbnailing a 1k-frame animation is
prohibitive, even a small resolutions), this was a behaviour change
from without thumbnailing -- animated gifs did not display inline at
all anymore.
Switch to thumbnailing as many frames as we can fit into a pixel-based
animated thumbnailing threshold, with a minimum of three (to be able
to convey that the image is actually animated). Smaller-resolution
images will hence get more frames in their preview. This also allows
the standard animate-on-hover or always-animate behaviour to be true
to their configurations, without confusing edge cases.
Fixes: #32609.
8bd8a33dd2