Hide config digest for manifest list tags

What does this MR do and why?

Hide config digest for manifest list tags

For docker multi-arch builds, manifest lists/indexes do not have associated config file, so Return an empty string when config digest is no... (!137709 - merged) will return empty string in some cases. This needs to be handled from the UI.

Screenshots or screen recordings

Before	After

Configuration digest row shouldn not be visible.

How to set up and validate locally

Based on discussion, it is a bit tedious to set up the metadata DB on the container registry, ideally it should be:

1. Setup & enable Container Registry https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/registry.md
2. copy a multi arch image from DockerHub to your local instance. Even easier if you use crane (copy docs):

   crane copy alpine:latest gdk.test:5000/gitlab-org/gitlab-test/alpine:latest --insecure

3. Visit Project > Deploy > Container registry.
4. click on recdntly pushed image
5. Verify config digest is not displayed

Until the discussion is resolved, alternatively you can apply the following patch to verify the UI

diff --git a/app/assets/javascripts/packages_and_registries/container_registry/explorer/components/details_page/tags_list_row.vue b/app/assets/javascripts/packages_and_registries/container_registry/explorer/components/details_page/tags_list_row.vue
index 3796c5440f71..c29779f155a4 100644
--- a/app/assets/javascripts/packages_and_registries/container_registry/explorer/components/details_page/tags_list_row.vue
+++ b/app/assets/javascripts/packages_and_registries/container_registry/explorer/components/details_page/tags_list_row.vue
@@ -120,7 +120,7 @@ export default {
       return this.tag.path?.replace(`:${this.tag.name}`, '');
     },
     isEmptyRevision() {
-      return this.tag.revision === '';
+      return true;
     },
     isInvalidTag() {
       return !this.tag.digest;

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #408863 (closed)