Remove the GameStreaming gate from AV1 HW LPLA path so that
non-GS applications with LookAheadDepth>0 can enter the HW
look-ahead pipeline.

- Widen Gate 2 predicate to allow any app with LAD>0
- Remove GS guard from LPLA hint application in UpdateTask
- Split UpdateTask into NewLA and OldLA branches

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>