Don't cache arrays of query results in a single cache bucket

[ryan]

We have started using one cache bucket per query with passive invalidation controlled through a last_changed incrementor. See #22024 for an example. We also need to do this with get_pages(), wp_get_archives(), and elsewhere. On wordpress.com we have hacked some of these into separate buckets because saving multiple queries per cache bucket results in huge buckets. We have seen 72MB get_pages caches. Let's finally clean this up for good. Some of the last_changed work done for #22176 can be used here.

See #23167 for get_pages(). This ticket can be a tracking ticket for all such changes.

#23206 for wp_get_archives()

Looking at [23300], are we going to do function_exists( 'wp_cache_incr' ) or can we mandate that all the object cache backends implement it?

Maybe wrap that logic in wp_bump_last_changed( 'post' )? Although if plugins like W3 Total Cache updated for 3.4 we might be able to drop the checks.

#23326 for get_terms()

#23327 for get_bookmarks()

get_calendar() also looks like a good one to update. It can invalidate with the posts last_changed.

If we introduce wp_cache_get_multi(), perhaps we should consider finally splitting alloptions and notoptions into individual cache buckets.

In 23384:

Use incrementors for cache invalidation in get_terms().

fixes #23326
see #23173

In 23385:

In wp_get_archives(), cache queries to individual cache buckets instead of storing them in one cached array. Use incrementor style passive cache invalidation.

fixes #23206
see #23173