[Notif redesign] Bigger "small" icon in old media notif

Note that notification_2025_template_collapsed_media is a fork of
notification_template_material_media.

Bug: 378660052
Test: visual test, screenshot tests to come later
Flag: android.app.notifications_redesign_templates
Change-Id: If09733114ebed073cf6fbbe7da3ceaa72544d47a