Revert "[//gpu] Compute overlay support properly on Ozone in SIManager"

This reverts commit 7a7e8c8e8933ea132d93b9efbe4b16e7a5c39cdf.

This turns out to not be a workable approach:

* The GPU service must create SharedImageCapabilities on its creation
  in order to send it back to the browser
* With the approach in the CL being reverted here, getting the
  SharedImageCapabilities on OzoneDRM queries the primary DRM device
  for whether it's atomic
* Querying whether the primary DRM device is atomic in the GPU process
  must block until the primary DRM device is made available from the
  browser
* However, the browser sends the primary DRM device only in InitOzone(),
  which GpuHostImpl calls directly after its call to create the GPU
  service (in fact, it doesn't even call it directly at that point but
  posts a task to call it)

Ozone initialization would have to be folded into GPU service creation
in the GPU process for this approach to work.

Bug: 330865436
Change-Id: I820e516ac3af4189ef0d1fe3b778648c10dea3f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5999542
Commit-Queue: Colin Blundell <blundell@chromium.org>
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1380191}