[controller] Reduce log level for no-op branch of UpdateFunc

[armingerten]

Which component:
controller version 2.17.0

Is your feature request related to a problem? Please describe.
Whenever the spec of a sealed secret is updated, the informer will trigger the UpdateFunc twice: Once for the actual change of the spec and a second time due to the change of the the status sub resource that is updated by the controller. This leads to confusing log output like this:

time=2024-12-15T02:47:42.194Z level=INFO msg=Updating key=foo/bar
time=2024-12-15T02:47:42.316Z level=INFO msg="Event(v1.ObjectReference{Kind:\"SealedSecret\", Namespace:\"foo\", Name:\"bar\", UID:\"919b1d17-3cb2-43c8-8a3b-8884218c6df6\", APIVersion:\"bitnami.com/v1alpha1\", ResourceVersion:\"1450095925\", FieldPath:\"\"}): type: 'Normal' reason: 'Unsealed' SealedSecret unsealed successfully"
time=2024-12-15T02:47:42.327Z level=INFO msg="update suppressed, no changes in spec" sealed-secret=foo/bar

While the log output makes sense when familiar with the controller, it is rather confusing from a user's perspective.

Describe the solution you'd like
Change the log level to Debug for:

sealed-secrets/pkg/controller/controller.go

Line 133 in e70e158

slog.Info("update suppressed, no changes in spec", "sealed-secret", key)