Move openEuler job to experimental pipeline

OpenEuler job fails 100% of the time. As discussed in QA meeting,
we agreed to move OpenEuler job to experimental pipeline.
- https://meetings.opendev.org/meetings/qa/2022/qa.2022-03-22-15.00.log.html#l-76

Once it is fixed, we can think of adding back to regular pipeline.

Change-Id: I831889a09fabe5bed5522d17e352ec8009eac321

Author: Ghanshyam Mann

.zuul.yaml

@@ -849,7 +849,6 @@
         - devstack-platform-centos-8-stream
         - devstack-platform-centos-9-stream
         - devstack-platform-debian-bullseye
-        - devstack-platform-openEuler-20.03-SP2
         - devstack-multinode
         - devstack-unit-tests
         - openstack-tox-bashate
@@ -948,6 +947,7 @@
 
     experimental:
       jobs:
+        - devstack-platform-openEuler-20.03-SP2
         - nova-multi-cell
         - nova-next
         - neutron-fullstack-with-uwsgi