Remove/update default bus-uri from services

[ashcrow]

A default bus-uri was set pre-release for testing. It should be removed or updated to better default.

Example: https://github.com/mbarnes/commissaire-service/blob/8123d85562a7d72bdf204fd3f8330b83e3219b43/src/commissaire_service/clusterexec/__init__.py#L287

[mbarnes]

What constitutes a "better" default? Is it the redis part that's objectionable?

[ashcrow]

@mbarnes a better default could be redis if we decide that redis is the default expected "bus". Right now we don't define one we expect as a default and we have been using redis for testing.