Update plugins to conform to new output delegator

[andrewvc]

Given the issues presented in #5662 we need to mass update all plugins to use the correct concurrency strategy (introduced in #5752).

We need to figure out which plugins will use :single, :shared, or :legacy_worker as concurrency strategies.

Ideally none would use :legacy, but time likely does not permit that. High impact plugins should be converted to shared if they actually are concurrent if possible. This means moving away from a worker model for these plugins however. This is advantageous for some plugins, like output-rabbitmq, which can use shared to more efficiently use the connection (RMQ does channel multiplexing over TCP connections).

Many other plugins, like stdout should move to the :single model, which disables the workers setting and allows only a single synchronized instance.

Some plugins need to move because they use the legacy instance method workers_not_supported. These plugins are:

• stdout
• file
• zeromq
• tcp (jsvd)
• s3 (ph)