Training areas taking time to load

[jeafreezy]

Sometimes, the training areas don't show up on the initial load.

To Reproduce

Steps to reproduce the behavior:

1. Go to https://fair-dev.hotosm.org/ai-models/365/training-area
2. Login if you haven't already.
3. See the delay before showing the training areas on the map.

Expected behavior

The training area should load up immediately after the page is mounted, or at least after the training areas are listed on the side panel; we should see them on the map, too.

Additional context

Given that we can't control the user's internet speed, we might need to show an indicator letting them know the training areas are loading.

[jeafreezy]

#348 should fix this.