graphics: remove non-HAL pixel formats

HALs are not expected to see YCBCR_422_888, YCBCR_444_888,
FLEX_RGB_888, and FLEX_RGBA_8888.  JPEG is purely wrong.

Note, current.txt change (as opposed to addition) is only allowed
because this is an unreleased interface.

Bug: 32593292
Test: builds
Change-Id: I432e6cb75cfc347a41e8e1632ae1898eed3350c8