[Notif redesign] Update Call/ConversationLayout alignment to new icon size

Note that notification_2025_conversation_header is a fork of notification_template_conversation_header.

Also removed an unused field in CallLayout.

Bug: 378660052
Test: visual test, screenshot tests to come later
Flag: android.app.notifications_redesign_templates
Change-Id: Ifa63ae58f2e306661a9f7e93e69dcd6e95c63546