Add test to check category-delete error message
Add test to check category-delete error message

Test case check that error message after calling category-delete with
non existing category name contains user friendly substring

Targets: blueprint murano-cli-integration-test-coverage

Change-Id: I44885bcf8e5735a89ee418358184169853024113

openstack/python-muranoclient,openstack/python-muranoclient