App store takes a long time to load applications when Flathub remote is installed

### What Happened?

Every time App Store is opened it takes a long time to pull the application list. Meanwhile, the categories are displayed which occupy too much space for what they are used for (if you click in one of them, as the applications are still loading, the button does nothing).

### Steps to Reproduce

1. Have an elementaryOS system.
2. Download one flatpak from flathub.com using elementary's installer. You'll notice flathub remote is added to the list.
3. Open AppStore. Notice it takes a considerable time to show just a few apps (20s the banner and 30s the applications). Meanwhile, applications from flathub are only shown on search, but not in the feed. This occupies unnecesary space and adds

### Expected Behavior

**Possible solutions:**
1. Ignore all remotes except elementaryOS.
2. A loading screen while apps are loading would be helpful. It's not too noticeable with a good internet connection, but people with worse internet or flathub its annoying to have to wait 30s for every appstore opening.
3. Cache popular apps and refresh them on the go asynchronously.
4. *Design issue:* while loading applications, categories are shown below. However, opening them is not useful because applications aren't loaded yet. This occupies unnecessary space and adds uncertainty to appstore.

### OS Version

7.x (Horus)

### Software Version

Latest release (I have run all updates)

### Log Output

_No response_

### Hardware Info

_No response_