Draft: Upgrade greengrass-bin to latest
The append file for greengrass-bin was used to force greengrass-bin from 2.9.5 to 2.12.10. Since meta-aws has now updated greengrass-bin to 2.12.6 this append file is now downgrading greengrass-bin.
Remove the parts of the append file which pinned SRC_URI It should be possible to remove this file entirely soon (see !275 (merged))