Missing event - ErrorinPrepareForMaintenance

### problem

If an error occurs when enabling maintenance mode, no corresponding event is created.

Events:

### versions

ACS: 4.22.1.0

### The steps to reproduce the bug

Example how to reproduce:
1. Create enough VMs to use up almost all available memory in the cluster
2. Enable Maintenance for one host
3. ErrorinPrepareForMaintenance will show up on the host
4. Check Events - no error is generated

### What to do about it?

_No response_

No source file or test is named. Reproduce the failure by enabling maintenance on a host under cluster memory pressure, then trace the maintenance-mode error event path and review open pull request #13669; done means an ErrorinPrepareForMaintenance event is created and the relevant event behavior is covered by tests.

Written by the indexing model from the issue text.