Drop CBDATA debugging (#1199)

Drop CBDATA debugging (#1199)

This was occasionally (but still rare) useful when CBDATA was the
only method of passing callback parameters. Much of that has now
been replaced with AsyncJob/AsyncCall logic. Making this debug
much less useful.

Remove the --enable-debug-cbdata build option and two cache manager
reports only enabled when that option is built. Greatly reducing
the cbdata logic complexity and removing one of its five APIs
permutations entirely.