UnreadCards: Drop unused `presences` prop.
UnreadCards: Drop unused `presences` prop.

We stopped using this in the recent refactor fc212ce47 applying to
many components.  It was missed here because of the unfortunate
`restProps` pattern.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile