[FIX] website: allow to re-edit social media title

This commit allows you to change the title of the social media block
after the first save. If an element is in a parent that has the class
`o_not_editable` then it is only editable if it has the contenteditable
attribute set to true. We rightfully remove this attribute at saving but
without putting it back when we return to edit mode. This commit allows
to fix this case. Note that we have to improve this system in the future
(so we can get rid of this patch).

This part of the fix is very similar to [this other fix] for the team
block.

[this other fix]: https://github.com/odoo/odoo/commit/b7d53d2fcb20a447fd3098adf94ffb33bc49dda9

task-3073171

closes odoo/odoo#133860

Part-of: odoo/odoo#105964
X-original-commit: https://github.com/odoo/odoo/commit/ba485b12bf9bc02644e743c7f236ce6492f453bc


Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>
Signed-off-by: Guillaume Dieleman (gdi) <gdi@odoo.com>