[16.0] missing discard button in non editable form

[niyasraphy]

Impacted versions: 16.0 and higher

Steps to reproduce:

• open any non editable form view(where we can perform create)
• for example, Blacklisted Phone Numbers menu from SMS Marketting -> Configuration -> Blacklisted Phone Numbers
• open form view, enter phone number, imagine now user need to stop the creation, there is no option
• the record has to be saved and then deleted

Current behavior:
missing discard option before saving

Expected behavior:
show the discard button

Support ticket number submitted via odoo.com/help (optional):