Drop Murano

It's inactive and hasn't produced a 2024.1 release [1].
In addition to that, there's a CVE that hasn't really been patched [2].

Also drop outward_rabbitmq that was used only with Murano.

[1]: https://governance.openstack.org/tc/reference/emerging-technology-and-inactive-projects.html#current-inactive-projects
[2]: https://lists.openstack.org/archives/list/openstack-announce@lists.openstack.org/thread/4FYM6GSIM5WZSJQIG4TT5Q3UBKQIHLWX/

Change-Id: I691205730b0e10a42ce61f3340cc39ee51bd1010