Increase linux machine from medium to large

[minorgal]

CircleCI contact says that increasing our number of cpus will make the build run faster. Can you try increasing for the current which is medium (must be the default) to large. https://circleci.com/docs/2.0/executor-types/

[tthef]

@minorgal the orb build commands are not actually used on native-modules, where we hurt most, but that's easily addressed there (and gives about 30% reduction in build time). I don't know if we want to use the large resource for the other packages, the build times there are much shorter, and just randomly looking at the timings quite a lot of it is in the pre-build setup where we probably won't gain that much?