Remove unwanted images in Gold

These extra outputs were caused by recent changes to
push_codec_srcs.
https://codereview.chromium.org/1327433003/

*** First, I would argue that we do not want to test
"native" modes (ex: codec, scanline, etc) to scales
that require sampling (ex: 0.1, 0.2, etc).  Right now,
we are trying to scale jpegs to 0.1, settling for 0.125
as the closest option, and then trying to compare the
0.125 scaled image to the actual 0.1 scaled image in
Gold.

*** Second, I messed up and caused our test setup to
try to decode to kIndex8 and kGray8 "always" instead
of only when it is recommended.  The bad effect of this
happens because we can decode jpegs to kGray8 even if
they are color images.  Right now in Gold, we have a
bunch of untriaged gray versions of color images.

The second issue would have been caught if we signaled
a fatal failure for invalid conversions.  Maybe we should
look into this now that 565 is supported everywhere?

BUG=skia:

Review URL: https://codereview.chromium.org/1314163007
1 file changed