Bug 1836034

Description of problem:

Since 4.2, new installations deploy hosted_storage as Master to start with, without the need for an additional SD to initialize the DC (which becomes master).

Currently, the way to change the Master role is to put the current Master in maintenance. But a user cannot get hosted_storage as master on systems initially installed on older versions, as it is not eligible to become master. What happens is that instead of the engine picking up hosted_storage as the new master, the DC simply goes into maintenance.

Due to this:
https://github.com/oVirt/ovirt-engine/blob/ovirt-engine-4.3/backend/manager/modules/bll/src/main/java/org/ovirt/engine/core/bll/storage/domain/StorageDomainCommandBase.java#L333

Which was introduced several years ago by:

~~~
commit c11bb0874aa1948724b35ebd367456e5fb5b75c1
Date:   Mon Jan 18 14:52:06 2016 +0200

    core: hosted engine: Avoid choosing the hosted engine sd as master
    
    Hosted engine domain will be under domain-monitoring in bootstrap mode and
    when there is no pool and that prevents VDSM in connecting it to the
    pool. to avoid further locking and special treatment we have for SPM we
    would completly avoid using that domain as master.
    
    Change-Id: Idd42aa656bea838059aaa274c91e7a5400b3b797
    Bug-Url: https://bugzilla.redhat.com/1298697
~~~

Does this still make sense? HE deployment is different now, and hosted_storage is Master on any new installation.

Version-Release number of selected component (if applicable):
rhvm-4.4.0-0.34.master.el8ev.noarch

How reproducible:
100%

Steps to Reproduce:
1. Install standalone RHV-M
2. Add 2 Storage Domains
3. Send one SD to maintenance, the other becomes master
4. Activate again
5. Create VM named "HostedEngine", with a disk on the non-master SD
6. Make it a fake hosted-engine (so that is_hosted_engine_storage is True)
   engine=# update vm_static set origin=5 where vm_name='HostedEngine';
7. Switch the Master to maintenance
8. Now the entire DC is in maintenance, the remaining SD is up but did not pickup the master role.

Actual results:
DC is in maintenance, hosted_storage not master

Expected results:
DC is Active, hosted_storage is master