When resizing a viewport all engine instance data was cleared. This wasn't the intended design and lead to performance regressions in the image engine. This patch makes sure that the instance data isn't cleared when the viewport size changes. When using instance data, draw engines are responsible to update the textures accordingly. This could also reduce flickering/stalling when resizing the viewport in eevee-next. Fixes T95428. Reviewed By: fclem Maniphest Tasks: T95428 Differential Revision: https://developer.blender.org/D14874