Describe the bug

With the new onboarding flow, the app and audio language screens have been redesigned, intorducing new behaviour. Some of this behaviour is buggy.

• On selecting an app language from the dropdow, the selected language in the options multi-pane panel sometimes does not update. Investigations show that this is due to the presenter originally relying on the result of translationController.updateAppLanguage(profileId, selection) to update the UI, but this is incorrect since this function's response payload is the _previous_selection.
• In the Audio Language dropdown, Swahili is listed as as supported language when it shouldn't be. Selecting Kiswahili returns LANGUAGE_UNSPECIFIED, which leads to the options side panel becoming blank.

Steps To Reproduce

1. Enable the ONBOARDING_FLOW_V2 feature flag.
2. Log in to the app and navigate to the options -> preferred app language/preferred audio language screen.
3. Attempt to change either language options
4. See that the decribed bug is reproduced.

Expected Behavior

1. The app language should be updated in the side panel as soon as it is updated in the language dropdown
2. Kiswahili should not show in the list of audio languages.

Screenshots/Videos

What device/emulator are you using?

Pixel Tablet 10"

Which Android version is your device/emulator running?

API 29

Which version of the Oppia Android app are you using?

No response

Additional Context

No response