Backport image improvements 5.1.6

[wezell]

This backports the fixes from #23384

[dsolistorres]

🔴 QA Failed — this backport breaks all server-side image processing out-of-the-box (every /contentAsset/image/... request → HTTP 404, provider == null!).

Root cause: ImageFilterApiImpl.deregisterProviders() calls deregisterServiceProvider(null) because the hard-coded default SPI net.sf.javavp8decoder.imageio.WebPImageReaderSpi isn't in 5.1.6's dependency set (this backport uses TwelveMonkeys 3.7.0 webp instead). Needs a null guard (and/or a corrected default class name).

Full root cause, reproduction, evidence, and confirmed fix in the issue: #36226 (comment) — #36226 (comment)