[v9.5.x] Licensing: Pass func to update env variables when starting plugin (#74681)

* Licensing: Pass func to update env variables when starting plugin (#74620)

(cherry picked from commit 5e0b20266e)

pkg/plugins/manager/loader/initializer/initializer_test.go

@@ -422,7 +422,7 @@ type fakeBackendProvider struct {
 }
 
 func (f *fakeBackendProvider) BackendFactory(_ context.Context, _ *plugins.Plugin) backendplugin.PluginFactoryFunc {
-	return func(_ string, _ log.Logger, _ []string) (backendplugin.Plugin, error) {
+	return func(_ string, _ log.Logger, _ func() []string) (backendplugin.Plugin, error) {
 		return f.plugin, nil
 	}
 }