Update CircleCI config #4775
Description
Summary
The CI for cosmos-sdk is in need of some maintenance. The CircleCI config file is too verbose and not making use of version 2.1 features.
The Makefile has unused targets and needs to be cleaned up.
Problem Definition
To speed up CI during each PR and make the configuration more readable.
Proposal
Refactor the CircleCI config and Makefile.
For Admin Use
- Not duplicate issue
- Appropriate labels applied
- Appropriate contributors tagged
- Contributor assigned/self-assigned