availableupdates: Refactor getting desired/current architecture

The commit does change the default behaviour of the
`getDesiredArchitecture` method. However, the method is only used once
in the `syncAvailableUpdates` method and nowhere else. The commit adds
the subsequent logic for evaluating a desired architecture to the method
itself and implements the `getCurrentArchitecture` method.

The goal is to introduces "getters" for such values where the
unified capitalization is enforced, and their return values are of the
same nature (e.g., "Multi", "amd64", ...).

Author: DavidHurta

pkg/cvo/availableupdates.go

@@ -49,15 +49,7 @@ func (optr *Operator) syncAvailableUpdates(ctx context.Context, config *configv1
 
 	channel := config.Spec.Channel
 	desiredArch := optr.getDesiredArchitecture(config.Spec.DesiredUpdate)
-	currentArch := runtime.GOARCH
-
-	if optr.release.Architecture == configv1.ClusterVersionArchitectureMulti {
-		currentArch = string(configv1.ClusterVersionArchitectureMulti)
-	}
-
-	if desiredArch == "" {
-		desiredArch = currentArch
-	}
+	currentArch := optr.getCurrentArchitecture()
 
 	// updates are only checked at most once per minimumUpdateCheckInterval or if the generation changes
 	optrAvailableUpdates := optr.getAvailableUpdates()
@@ -330,7 +322,14 @@ func (optr *Operator) getDesiredArchitecture(update *configv1.Update) string {
 	if update != nil {
 		return string(update.Architecture)
 	}
-	return ""
+	return optr.getCurrentArchitecture()
+}
+
+func (optr *Operator) getCurrentArchitecture() string {
+	if optr.release.Architecture == configv1.ClusterVersionArchitectureMulti {
+		return string(configv1.ClusterVersionArchitectureMulti)
+	}
+	return runtime.GOARCH
 }
 
 func calculateAvailableUpdatesStatus(ctx context.Context, clusterID string, transport *http.Transport, userAgent, updateService, desiredArch,