(maint) Pull out Sid and Unstable
(maint) Pull out Sid and Unstable

This commit pulls out Sid and Unstable from build_defaults, they are no
longer supported.

ferventcoder/hiera,Iristyle/hiera,MikaelSmith/hiera,johnduarte/hiera,johnduarte/hiera,MikaelSmith/hiera,ferventcoder/hiera,Iristyle/hiera,ferventcoder/hiera,Iristyle/hiera,MikaelSmith/hiera,johnduarte/hiera