`PhoneInput` edge-case related to selecting prefix via-dropdown

[Lordfirespeed]

To reproduce

1. Select prefix (e.g. +44)
2. Fill out valid phone number (e.g. 1234 567890)
3. Select a different prefix via drop-down

Actual result

The input text is cleared but the old prefix is still selected (i.e +44)

Expected result

The input text is cleared and the new prefix is selected