Management Server does not recognize a session as removed in some scenarios

### Problem Description

In some scenarios, the Management Server does not recognize that a console session has been released. As a consequence of that, the `removed` column of the `cloud.console_session` table remains indefinitely marked as `NULL`.

### Versions

ACS versions 4.19 and 4.20

### The steps to reproduce the bug

- https://github.com/apache/cloudstack/pull/11016#pullrequestreview-2993780512 and https://github.com/apache/cloudstack/pull/11016#issuecomment-3052399701 describe two different situations in which this bug occur.

### What to do about it?

Normalize these scenarios, ensuring that the `removed` attribute of console sessions is corretly set to the datetime in which the sessions are released.

Start by reading the two scenarios described in the review and comment on pull request #11016, then trace how the Management Server records console-session release events. Verify the behavior against the cloud.console_session table, and consider the work complete when each reported scenario sets removed to the release datetime instead of leaving it NULL.

Written by the indexing model from the issue text.