WL#2512: Use global cache for all meta-data in handler

Currently there is two-level caching of meta-objects (tables
and indexes) in the handler. Only the global cache has reference 
counting. This causes handler instances sometimes to get stale 
meta-object references to altered tables (or rebuilt indexes) 
when being passed between threads. If the alter table is done 
in the same MySQL server then using global cache only would allow 
for detecting this without needing retries (for alter tables in 
other servers retries will still be needed). To implement this 
the local cache in the ndb objects need to be bypassed for the handler.
(It cannot be removed since it is still useful for applications 
using NDB API directly).