Fixes: #17923, #17921 - Fix non-null constraint for script execution

[alehaa]

Fixes: #17921

With c34a0e2, validation of job object fields is enabled, so ScriptJob must not set required fields to empty strings. Changes of this PR revert b18f193 and (hopefully) fix this issue not only for UI views, but for all interactions with scripts.

[miaow2]

The proposed fix will set Run Script as the default name for all future job names initiated by custom scripts, which may lead to confusion.

I believe a more effective solution would be next:

1. add name=script.name here to fix running scripts from CLI

job = ScriptJob.enqueue(
    instance=script_obj,
    user=user,
    immediate=True,
    data=data,
    request=NetBoxFakeRequest({
        'META': {},
        'POST': data,
        'GET': {},
        'FILES': {},
        'user': user,
        'path': '',
        'id': uuid.uuid4()
    }),
    commit=commit,
    name=script.name,
)

2. add name=script.name here to fix running scripts from API

ScriptJob.enqueue(
    instance=script,
    user=request.user,
    data=input_serializer.data['data'],
    request=copy_safe_request(request),
    commit=input_serializer.data['commit'],
    job_timeout=script.python_class.job_timeout,
    schedule_at=input_serializer.validated_data.get('schedule_at'),
    interval=input_serializer.validated_data.get('interval'),
    name=script.name,
)

3. add name=job.name here to fix jobs scheduling

cls.enqueue(
    instance=job.object,
    user=job.user,
    schedule_at=new_scheduled_time,
    interval=job.interval,
    name=job.name,
    **kwargs,
)

4. remove name attribute from Meta class here because it's empty and the parent class JobRunner already has classproperty name that will be called if empty name are passed to enqueue method

[alehaa]

I've added d0ee689 to cover the name being reused when the job is rescheduled. Thanks @miaow2!

For points 1 and 2 mentioned in the comment above, I'd like some feedback from maintainers. Since this is a cosmetic change, there may not be a good or bad design, just a decision based on feeling.

[jeremystretch]

IMO naming the job "run script" is acceptable, because that's what it's doing, and each job retains a relation to its corresponding script.

[jeremystretch]

I'm accepting this as a fix for #17921 specifically. Will re-evaluate #17923 separately to see if any additional work is required for that bug. Thanks @alehaa!