feat: allow skip scaled object creation with config

[frankliu20]

When integrate Keda-Http with other KEDA scalers, we want to manage ScaledObject by ourselves, and add http-scaler as one of the triggers. In this PR, we allow users to do such ScaledObject management. When flag SKIP_SCALED_OBJECT_CREATION is set to true, keda-http-operator will skip the ScaledObject creation.

Checklist

• Commits are signed with Developer Certificate of Origin (DCO)
• Changelog has been updated and is aligned with our changelog requirements
• Any necessary documentation is added, such as:
  • README.md
  • The docs/ directory
  • The docs repo

[JorTurFer]

I think that this is a nice feature and simplifies the compatibility between KEDA and the HTTP add-on because avoid the requirement of implementing the whole ScaledObject spec in the add-on. WDYT @tomkerkhove @t0rr3sp3dr0 ?

@frankliu20 , Could you add an e2e test for testing this feature? IMO this requires an update in docs to explain that this can be done for other users

[t0rr3sp3dr0]

I like the idea but would rather have this as a field in the HTTPSO definition instead of an Operator argument. That way, you could have some services using the managed SO while others use a custom one.

[JorTurFer]

@frankliu20 , any update?

[muecahit94]

Hi, any updates on that feature?

I would like to use zero scaling feature, but for that I need a combination of a keda built-in trigger and the http trigger, at the moment its not possible.

[JorTurFer]

It looks that the PR has been abandoned by the OP :(
Are you willing to continue it @muecahit94 ?

[muecahit94]

@JorTurFer tbh no, just wanted to ask if there are any updates

[devopsdynamo]

@JorTurFer Hi, I'm happy to pick this up and raise a new PR for this as I've already made the required changes for this feature on our forked repo.

[devopsdynamo]

I've opened up new PR to allow annotation to be set on the HTTPSO instead as this allows more flexibility.
#929

[JorTurFer]

This feature is already done by #929