Simplify cache tags to avoid long header length

Should we be piggy-backing on the work being done inside https://www.drupal.org/project/purge/issues/2952277 ✨ Minify the cache tags sent in the header Needs work instead? They've got quite a few options for simplification that we can tap into.

I went ahead and created the patch assuming we go with purge's forthcoming changes. Once we pick a path we can get the issue fork resolved.