Subiquity states passwords do not match if password first started in confirm field

[John Lettman]

There is a very minor errant behavior when creating the first account on an install. When a password is first typed into the "Confirm your password" and does not match the "Choose a password" field, any further updates to the "Choose a password" yield the "Passwords do not match" error despite matching.

This is fairly easy to reproduce:

Type "qwerty" in "Choose a password"
Type "asdf" in "Confirm your password"
Change "Choose a password" to "asdf" (matching "Confirm your password")

The "Passwords do not match" error should persist despite both fields containing identical values.

[John Lettman (jplettman)]

A possible fix?

https://github.com/canonical/subiquity/blob/ad18b58f4e37c13b4ead89b809a5f5da46c48e88/subiquity/ui/views/identity.py#L154

duplicating the signal for the "Choose a password" field.