Fixtures: Make daemon_client function scoped

This is more expensive than the original idea of having it session
scoped since now the daemon is stopped after each function usage,
however, not stopping the daemon can cause tests to fail if previous
tests leave it in an inconsistent state.

aiida/manage/tests/pytest_fixtures.py

@@ -241,7 +241,7 @@ def get_code(entry_point, executable, computer=aiida_localhost, label=None, prep
     return get_code
 
 
-@pytest.fixture(scope='session')
+@pytest.fixture()
 def daemon_client(aiida_profile):
     """Return a daemon client for the configured test profile for the test session.