Don't dim screenshots when there's no HDR on-screen.

Dimming the screenshot:
* Is incorrect for screenshots that leave the device
* For transitions, requires disabling dimming which reports to DisplayManager that the screenshot is HDR, which costs power.

Bug: 293560925
Bug: 298492174
Bug: 299055884
Flag: Exempt
Test: screen rotation with and without HDR
Test: systemui jank suite
Change-Id: Id6de2c8d3987300a1c24bf79dc5b523f40420174