Preload cache tags in cache getMultiple

Problem/Motivation

#3436146: Introduce a list of "frequent cache tags" to reduce lookup query amount adds preloading for cache tags.

I think we can make use of this in the cache backend itself, to preload tags when multiple cache items are requested at once.

This doesn't kick in very often with core performance tests but it's visible in the Umami authenticated test.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet