Problem/Motivation
#2226761: Change all default settings and config to fast/safe production values added the null and memory backends to the container, despite objections from me and catch. This clutters up the container, adding stuff back in for dev only purposes when we are striving for fast default values for this stuff.
Proposed resolution
Remove the null and memory backend definitions from core.services.yml and add these to devel module. This can then easily provide these so a dev env can utilise them
Remaining tasks
User interface changes
None
API changes
Clean up cache backends available out of the box. Delegate to devel module.