[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/backendplugin/grpcplugin/grpc_plugin.go

@@ -33,12 +33,12 @@ type grpcPlugin struct {
 
 // newPlugin allocates and returns a new gRPC (external) backendplugin.Plugin.
 func newPlugin(descriptor PluginDescriptor) backendplugin.PluginFactoryFunc {
-	return func(pluginID string, logger log.Logger, env []string) (backendplugin.Plugin, error) {
+	return func(pluginID string, logger log.Logger, env func() []string) (backendplugin.Plugin, error) {
 		return &grpcPlugin{
 			descriptor: descriptor,
 			logger:     logger,
 			clientFactory: func() *plugin.Client {
-				return plugin.NewClient(newClientConfig(descriptor.executablePath, env, logger, descriptor.versionedPlugins))
+				return plugin.NewClient(newClientConfig(descriptor.executablePath, env(), logger, descriptor.versionedPlugins))
 			},
 		}, nil
 	}