Fix SSA managed-fields type converter for scanner group

[ArnobKumarSaha]

Problem

Every write to a scanner.appscode.com/v1alpha1 object logs:

[SHOULD NOT HAPPEN] failed to update managedFields ... no corresponding type for
scanner.appscode.com/v1alpha1, Kind=ImageScanRequest

and metadata.managedFields is never populated.

Root cause

start.go built one ignore list for the OpenAPI v2 config — which excludes the scanner group prefix /apis/scanner.appscode.com/v1alpha1 — and then reused it for OpenAPIV3Config.

Server-side apply (GA) builds its managed-fields type converter from the v3 config: GenericAPIServer.getOpenAPIModels → getResourceNamesForGroup skips any resource whose path is under an IgnorePrefixes entry. Since api.SchemeGroupVersion.String() is scanner.appscode.com/v1alpha1, that prefix matches every scanner resource, so all of them are dropped from the converter's GVK→schema map → no corresponding type on every write.

Fix

Give the v3 config its own IgnorePrefixes = []string{"/swaggerapi"} instead of reusing the v2 ignore list. The scanner resources now reach the converter; the v2 published-spec behavior is unchanged.

Verification

go build ./... green. On a cluster running this build, an Update/Apply populates metadata.managedFields and the [SHOULD NOT HAPPEN] line is gone.