HTTPProxy's projectcontour.io/ingress.class gets removed after reconciliation

[frekw]

Describe the bug

When ContourRouter.Reconcile is ran, the projectcontour.io/ingress.class annotation gets removed. I think this is due to the fact that the annotation is only set upon creation, but during update we just grab the annotations and overwrite them, disregarding the fact that they may diff.

To Reproduce

Run flagger with -ingress-class and do a rollout.

Expected behavior

The ingress class to remain.

Additional context

• Flagger version: 1.33.0
• Kubernetes version: -
• Service Mesh provider: Contour
• Ingress provider: Contour

[KrylixZA]

I wonder if this is related to #1312 which unfortunately has been open for a long time.