Remove custom image from Gitpod configuration
On advice from @gtsiolis, we don't need to set a default image for Gitpod and, in fact, our image is incompatible: https://code.visualstudio.com/docs/remote/linux#_tips-by-linux-distribution.
On advice from @gtsiolis, we don't need to set a default image for Gitpod and, in fact, our image is incompatible: https://code.visualstudio.com/docs/remote/linux#_tips-by-linux-distribution.