[Notif redesign] Bigger "small" icon in base expanded notif

Note that notification_2025_template_expanded_base and
notification_2025_reply_container are forks of
notification_template_material_big_base and
notification_material_reply_text respectively.

Bug: 378660052
Test: visual test, screenshot tests to come later
Flag: android.app.notifications_redesign_templates
Change-Id: I1bfdfb71c0d9db36b9cb0978a38df2c1cfa3ab32