run_processor: do we really _always_ want to save_mets() ?

[bertsky]

core/src/ocrd/processor/helpers.py

Line 160 in 62cf25c

workspace.save_mets()

Now that we have the METS Server option, we should reconsider this behaviour. It gets used in both the standard processor CLI (via ocrd_cli_wrap_processor) and in ocrd_network (via invoke_processor).

At least the latter should be able to opt out of intermediate METS serialization. (Should only be done when stopping the METS Server.)