Camera: Narrow down cases preview spacer is used

HW_TEXTURE usage flag may be used for ImageReader. Do not treat the
surface as SurfaceTexture if the surface has CPU read flag at the
same time.

In addition:
- Only enable preview spacer if timestamp base is DEFAULT,
- Use readoutTimestamp for re-spacing.
- Remove the system property to disable frame spacing.

Test: Camera CTS, Observe smoother GCA photo preview
Bug: 195025014
Change-Id: I40a3b1acac44ed8a474aad94b77aee8f7399eb31