software/erp5/test: use short partition references

These partition references should be kept short, they are a mechanism
to use a short path for unix sockets, because unix socket paths can not
exceed 108 characters.

When running the test in theia, this was causing errors:

   # [ALERT]    (100453) : config : parsing [/srv/slapgrid/slappart15/srv/runner/instance/slappart7/tmp/inst/with-max-rlimit-nofile6/etc/haproxy.cfg:37] : log : socket path '/srv/slapgrid/slappart15/srv/runner/instance/slappart7/tmp/inst/with-max-rlimit-nofile6/var/run/log.sock' too long (max 97

software/erp5/test/test/test_erp5.py

@@ -1104,7 +1104,7 @@ class TestNEO(ZopeSkinsMixin, CrontabMixin, ERP5InstanceTestCase):
 class TestWithMaxRlimitNofileParameter(ERP5InstanceTestCase, TestPublishedURLIsReachableMixin):
   """Test setting the with-max-rlimit-nofile parameter sets the open fd soft limit to the hard limit.
   """
-  __partition_reference__ = 'with-max-rlimit-nofile'
+  __partition_reference__ = 'nf'
 
   @classmethod
   def getInstanceParameterDict(cls):
@@ -1123,7 +1123,7 @@ class TestWithMaxRlimitNofileParameter(ERP5InstanceTestCase, TestPublishedURLIsR
 class TestUnsetWithMaxRlimitNofileParameter(ERP5InstanceTestCase, TestPublishedURLIsReachableMixin):
   """Test not setting the with-max-rlimit-nofile parameter doesn't change the soft limit of erp5
   """
-  __partition_reference__ = 'unset-with-max-rlimit-nofile'
+  __partition_reference__ = 'nnf'
 
   def test_unset_with_max_rlimit_nofile(self) -> None:
     with self.slap.instance_supervisor_rpc as supervisor: