The default value of the required form option has been changed to false

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | a bit :)
| BC breaks?    | no
| Deprecations? | no
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

This feature will be introduce into SF 2.6. With this PR we could clean all the form and remove this option because we don't use html5 validation.
Please don't break line here...