Simplify client/server translator tests

Motivation:

The client and server translator tests have a lot of repetition. Now
that they are based on structured swift extension, which is tested
separately, the tests can be much briefer as the translators just glue a
few bit together.

Modifications:

- Remove a bunch of translator tests as they are already covered by
  lower level tests

Result:

Less maintenance burden

Author: glbrntt