The aws/codebuild/standard:6.0 image contained yarn. However the aws/codebuild/standard:7.0 does not. This is causing our codebuild's to fail as we rely on the yarn executable.

I can see lines in the aws/codebuild/standard:6.0 dockerfile installing yarn but these aren't in aws/codebuild/standard:7.0. Please could these lines be added back in so that the container image contains yarn.