Remove format option from newsletter form

[alexgibson]

Please describe the use case(s) for this component

Signing up for Mozilla related newsletters

Please describe the change you wish to see

Removal of the format input fields

Please describe why these changes need to be made

The email marketing team have asked to remove this option, as text based email are not supported by Braze (our new vendor).

Please provide any designs or prototypes of the proposed changes

Please describe where this component is currently in use

This form is used on many pages on mozorg.

Is the development of this component a blocking dependency for other work? Please explain if so

Desired due date: April 1, 2024

[reemhamz]

Didn't get a chance to work on this before the 1st of April, but I'm going to tackle this first thing tomorrow 🌞