Acitivity Log broken when referenced hostgroup is deleted or renamed

[BTMichel]

Describe the bug

If a host uses a hostgroup, which has been renamed of deleted, looking at activity log entries of that specific host, returnes an error and prevents viewing the specific activity log.
Note that this only affects activity log entries, where the host was member of the deleted or renamed hostgroup.

To Reproduce

1. Create Host A
2. Create Hostgroup B
3. Add Host A to Hostgroup B
4. Deploy the changes
5. Perform a change on Host A e.g. change its host address and open the specific activity log entry in another tab
6. Note that there shouldnt be any errors in that new tab, you should be able to see the change that was made
7. Deploy that change
8. Rename Hostgroup B to something else or delete it
9. Look at the activity log entry that was opened in another tab (Step 5)
10. It should now show an error message "The group 'B' does not exist"

Expected behavior

There should not be any error message viewing activity log entries of hosts with hostgroups that have been renamed or deleted.
You should be able to see the specific change that was made for that activity log entry.

Screenshots

Not applicable, see section To Reproduce

Your Environment

• Icinga DB Web version (System - About): 1.1.1
• Icinga Web 2 version (System - About): 2.12.1
• Web browser: Chrome
• Icinga 2 version (icinga2 --version): 2.14.1
• Icinga DB version (icingadb --version): 1.1.1
• PHP version used (php --version): 8.1.21
• Server operating system and version: RHEL 9.4

Additional context

This issue also affects icinga web 2 (the predecessor of icinga db web).