[RenderEngine] Convert BT2020 to SRGB by default.

Previously, we convert BT2020 color space to Display P3 by default. However,
converting it to SRGB makes HDR look visually better under saturated mode. This
patch makes sure we only convert BT2020 to Display P3 when Display P3 is
specified as output data space, and convert BT2020 to SRGB by default.

BUG: 72180957
Test: Build, flash, install customized Youtube app, watch HDR video.
Change-Id: I1ce6568b93fee620ff438b209bf6bb48e1006e83