Fix execution of client context tests.

When running the tests that can be executed either on server or client
context, without defining 'ipa_context', the context is automatically
identified.

Currently, the tests in upstream CI run only on a server, and the
context is identified as "server" context, and in order to run the test
using a client context 'ipa_context' must be set to 'client'.

This patch fixes all the client context tests by correctly setting
ipa_context when running the client context tests in a server host.