[dvsim] The launchers handle max_parallel very strangely

[rswarbrick]

Description

For some reason, this is handled in a static variable in each class, which gets set up at the start of the dvsim main function. That seems very strange!

The max_parallel argument should probably be passed through:

• FlowCfg.deploy_objects (called in three places in dvsim.py)
• Scheduler.__init__
• Deploy.create_launcher
• LauncherFactory.get_launcher