netcmd: Increase the transaction_index_cache_size to 200k for schemaupgrade

netcmd: Increase the transaction_index_cache_size to 200k for schemaupgrade

Increasing this value greatly improve the performances of schema
upgrade for large domains (>200k entries).

The value 200000 is chosen because it is already used in join.py, and
should be sufficient for known domains.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15795

Signed-off-by: Andréas Leroux <aleroux@tranquil.it>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>