Dont replace the feed with a loading symbol when updating

[litetex]

Checklist

• I made sure that there are no existing issues - open or closed - which I could contribute my information to.
• I'm aware that this is a request for NewPipe itself and that requests for adding a new service need to be made at NewPipeExtractor.
• I have taken the time to fill in all the required details. I understand that the feature request will be dismissed otherwise.
• This issue contains only one feature request.
• I have read and understood the contribution guidelines.

Feature description

From #7047:

• Dont replace the feed with a loading symbol, just update when loading is done.

Why do you want this feature?

Users with a lot of subscriptions are primarily affected due to the long loading time.
Non-blocking UI → Users can browse the feed while loading.

Additional information

See also #8511

[opusforlife2]

Especially when updating through an Invidious instance. The feed loading time becomes an order of magnitude slower.

[SameenAhnaf]

Duplicate of #4952

[opusforlife2]

With its overly generic title, it's not surprising we missed it.