Remove babel 7.0.0-bridge after Jest is upgraded

The following discussion from !23406 (merged) should be addressed:

• @winh started a discussion: (+1 comment)

  This is currently necessary for babel-jest:

  https://github.com/facebook/jest/blob/v23.6.0/packages/babel-jest/README.md

  https://github.com/facebook/jest/pull/7016 will fix that.