[keycloak-dev] Remember to close responses using admin client

[Stian Thorgersen]

For methods on the admin client that return a Response it's important to
remember to close it. Failing to do this causes:

* Not freeing up connections
* Tests can fail intermittently as the tx may not be completed before you
move on

Ideal would be to find a way to prevent this and have the admin client
close the responses, but I don't think that's possible.