Locale Selector is not populated upon immediate access to Settings page

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Steps to reproduce

1. Reinstall Pontoon Add-on from addons.mozilla.org. Do not sign in.
2. From the Introduction Tour, click Addon Settings within 10 seconds of installation.
3. Observe that the locale selector is empty, and does not populate until page reload.

Expected Behavior

The user should see a loading feature before the locale selector is populated.