address feedback on PR #28654

[HunterLarco]

Description

After being merged, additional feedback was provided on #28654 (see comment)

The example is unfortunately not in an ideal state since a black screen by default isn't good. Instead of using a lil-gui, what do you think about cycling through the layers (1, 2, 3) in a fixed interval?
If the E2E test fails, just add it to the exception list.

Alternatively, I could just initialize the example by writing the first 3 layers to the screen and then letting users navigate the dat.gui. Do you have a preference?

Let's use this approach since webgl_texture2darray_compressed is already animated.

This PR does just that, it updates the example to initialize with the first 3 layers of the spirited away reel.

cc @Mugen87

This contribution is funded by SOOT