chore:extracted the group monitor to a different monitoring type

[CommanderStorm]

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Description

This PR is part of the migration to monitoring-types.
I migrated the group monitor into a different monitoring type.
No actual code changes have been made, this is just a code move.

Type of change

• Other

Checklist

• My code follows the style guidelines of this project
• I ran ESLint and other linters for modified files
• I have performed a self-review of my own code and tested it
• I have commented my code, particularly in hard-to-understand areas (including JSDoc for methods)
• My changes generates no new warnings
• My code needed automated testing. I have added them (this is optional task)

Screenshots (if any)

previous	now

[no8ody]

Hello,

this PR presumably only affects the backend? Wouldn't it make sense to use this grouping for the frontend as well? As the servers in this group are not currently visible there and the entire group is displayed as "down" if a service fails

[CommanderStorm]

Wouldn't it make sense to use this grouping for the frontend as well?

The existing grouping functionality (see screenshots) was not changed. It is implemented in the frontend.

As the servers in this group are not currently visible there and the entire group is displayed as "down" if a service fails

Currently, groups are down if children.any(child=> child.is_down)

This is tracked in different issues and I decided not to include them to make reviewing eazier.
See these issues:

• conditional monitors: [groups] Conditional monitoring #2487
• hirachical/depenedent monitors: [groups] Dependent monitoring of hierarchical monitors #1089
• multi-group membership: [groups] Multiple group membership for monitors #4036
• Boolean OR: [groups] Boolean OR operand to get notification for total failure of redundant systems #3387