[Notif redesign] Update spacing of smart replies & actions

Changing the spacing around smart replies, smart actions and regular
notification actions to match the specs.

Note that notification_2025_action_list.xml is a fork of
notification_action_list.xml.

Bug: 378660052
Test: manual + screenshot tests
Flag: android.app.notifications_redesign_templates
Change-Id: Idf101b714690f290ca68bb0cc842592a66e58cdc