Remove GOP Settings Prompt about amplify-video

[wizage]

This will be changed in VoD branch. Will touch both livestream-questions.json & livestream-push.js

Example:

Would you like to use default settings?
> Default (explain)
  Sub 10 Seconds
  Advance

[smp]

After spending quite a bit of time thinking about this today, there's a few refactor projects necessary for live streaming:

• MediaLive and Mediastore should use native cfn now that we have it
• GOP / segment settings should be removed and replaced by specific medialive encoding templates
• We should allow arbitrary medialive templates to be provided/selected/uploaded by the user
• Origin selection should be largely abstracted away from amplify video user. We should ask things like "low latency" "DVR" or "Live to VOD" and then select the right origin for them (store/package). Perhaps in a radio button-multiselect form.

In the meantime, instead of adding more options, I'm going to gut the GOP settings prompts and hard-code them to the low-latency settings. Then, during larger refactor, we can evaluate the right way to expose different 'live streaming features' which is what I think we're trying to do by expressing these knobs, albiet in a half-hazard way at this juncture.

[wizage]

1. Chances of moving to ML to CF is low due to the missing features on CloudFormation (mainly start and stop). We will move if MediaPackage support comes but right now no benefit from moving.
2. As discussed above we should replace them temporary with a plain english description to fit the model of amplify.
3. Not related to this issue but I do agree. Please cut another issue for this.
4. If you want to do this instead of just removing this GOP, then I say go for it! This would be a huge win and can be scaled pretty easy to fit the other features as we make them. (This can be done now without a lot of other changes).

I would argue that at the point v1 is feature complete. We are in maintenance mode for v1 and upgrading only for security. So, the refactor can take place on the VOD branch and can go live when ever you are done.