Checkout: Improve client-side relay connectivity handling on checkout page

[danieldaquino]

In certain network conditions, an error may appear when loading a profile picture and name due to intermittent connectivity issues.

Although this is beyond our control, we could improve the checkout page in the following ways:

1. Add some automatic retry logic.
2. Make this specific error less alarming. Right now we show a pop-up, but since this issue does not impede the user from completing the purchase, we could make this error less conspicuous.