[no-frame-context-signaling] Fix coefficient CDFs in encoder
[no-frame-context-signaling] Fix coefficient CDFs in encoder

Commit https://aomedia-review.googlesource.com/c/aom/+/49984 fixed
an issue with the default coefficient CDFs on the decoder side,
but I accidentally left out the encoder-side changes.

BUG=aomedia:1521,aomedia:1527

Change-Id: I17c48f68ef2c8e45f2cbe5f8a555dd78b1704cba

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom