web: properly render password reset item in profile sidebar
Created by: kzh
This PR properly renders the password reset item in the profile sidebar when the user account uses builtin authentication. This fixes #7520 (closed). It also removes the existing logic (checking to see if builtin auth provider is enabled) that lead to false positives.
The builtin is detected when the password field in the users table is not null. (https://github.com/sourcegraph/sourcegraph/blob/master/cmd/frontend/db/users.go#L110)