Issue Description

cn=default indexes is a concept that can often trap people as they don't know what they do. They appears to be "global" indexes that apply everywhere, and in docs sometimes it could be read and interpreted as that.

However, they are actually a template of indexes to be created when a new backend instance is created. This would be common in a virtualhosting scenario where many backends are created at custom request and demand. They do nothing unless a new backend is made.

Sometimes we see people sometimes create indexes in default indexes, then wonder why it didn't help make their search faster. While this sounds like a docs issue, it's actually a design flaw in that we presented an interface that looks ilke it controls indexes, but does not.

Given that the virtual hosting scenario seems to be less and less, we should consider removing the default indexes from being in cn=config, opting instead to have these generated from within the ldbm plugin, or from within lib389 instead. What is the right way to do this I'm not 100% sure. Perhaps leaving default indexes as is for existing setups, but blanking them in template-dse.ldif, and having them created from lib389?