Remove video play icon and tap to play behavior for panorama.

Bug: 7258968

Per new UX design, there'll be a panorama viewer icon in the bottom
right instead (see b/7233446)

This is essentially a revert of Change-Id
I17fdb5d6bcab1f3997a1ab92fcf45e0309b394b3

Change-Id: Ib35c99cca4ee9b2422dd16f5ea3b931ad5f08f35