suffix index names with "_history" just like tables

suffix index names with "_history" just like tables

Fixed regression in history_meta example where the use of
:meth:`_schema.MetaData.to_metadata` to make a copy of the history table
would also copy indexes (which is a good thing), but causing naming
conflicts indexes regardless of naming scheme used for those indexes. A
"_history" suffix is now added to these indexes in the same way as is
achieved for the table name.

Fixes: #10920
Change-Id: I78823650956ff979d500bedbdbce261048894ce9