[FIX] website_form: prevent input field type change

The translation of input "default values" is allowed only when
`type="text"`. However, email field values are translatable because of
strange behaviour:

- Go to website (Edit mode) > Add a form block.
- Select the existing email field > Change label position > The input
is transformed into a `type="text"`.

Each time a "non-custom" field is re-rendered, The `_getActiveField()`
method is obtaining field related data from the database, including its
type, which changes it back to the original value ("char").

The goal of this commit is to fix this behaviour using `_getFieldType()`
to set the right field type instead of the default one.

task-3247520

closes odoo/odoo#119293

Signed-off-by: Outagant Mehdi (mou) <mou@odoo.com>