Resolve some trivial TODOs in generate_data()

[markmc]

Some pretty trivial changes to knock out some TODOs in generate_data()

commit 51df195

    Remove unused generate_data() parameters
    
    These parameters aren't being used by the only user of this method,
    and so they can be removed. They also aren't being used within
    generate_data().

commit e63bfbe

    Re-order generate_data() params to match CLI
    
    The CLI is the only user of this function, and we have some work
    to do to remove unused or defunct parameters. That's easier if
    they are listed in the same order as they are used!

commit 9d7c521

    Remove TODO about num_instructions_to_generate
    
    We have support for this parameter now.

commit 355ff30

    Remove defunct no-pipeline-defined error path
    
    We now have full and simple pipelines defined for knowledge, grounded
    skills, and freeform skills, so this error path can't be hit anymore.

[russellb]

Nice work. Thanks for doing the validation on which parameters are actually used. e2e passed, so I'm confident the basics of the interface with the CLI are still working fine