remove gatsby emotion plugin

[pettinarip]

After we finish the UI migration of all the components and pages, remove this plugin that is not needed anymore.

[TylerAPfledderer]

@pettinarip what's left at this point?

[pettinarip]

@TylerAPfledderer for the UI migration, just this and cleaning up some stuff like not using the SharedStyledComponents anymore, double check that we are not using styled anymore, removing deprecated components like Icon and OldEmoji. I'll do that today and close this epic.

The only component left to migrate is the react-select component that you already covered in this PR #10542. But that one is also doing the DS implementation. I'll try to get that one merged soon but I'll not consider it as necessary to close this epic.

After that, we could make tons of refactors but we will not include them in the scope of this epic. We can do them more organically as we implement the new components from the DS.

[corwintines]

@pettinarip I merged the above PR, I think this can be closed out now, but wanted to double check first.

[pettinarip]

Awesome, yes. Thanks!