[TreesInViz] Preserve OOM tiles but release existing resource if present.

When transitioning a tile to NoContents with MissingTileReason::kOutOfMemory,
we now preserve the tile object in the TileDisplayLayerImpl tiling map
instead of deleting it. This ensures metadata like tile coordinates and
transform are retained for potential future use to do checkerboarding.

If the tile previously held a TileResource, the associated GPU resource
is explicitly released before updating the tile's contents to reflect
the OOM state.

This decouples tile lifetime from resource ownership in the OOM case and
avoids prematurely deleting OOM tiles that are expected to be deleted later.

Bug: 417965009
Change-Id: Ie7b2231d5cb034f5d94fe4ef489c04df83a4ce11
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6554562
Commit-Queue: vikas soni <vikassoni@chromium.org>
Reviewed-by: Victor Miura <vmiura@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1462595}