Request high res icons for app pairs after all workspace items processed

* TL;DR Loading workspace icons only requests high res icons for apps
on workspace or in hotseat, not for folders or app pairs. They need to
request that separately
* See notes on bug for root cause

Test: Created many app pairs, empty icons does not repro.
If I remove my change issue consistently repros, not a race condition
Fixes: 323106492

Change-Id: I05ba5e8e8b0eddd4041642f89d06deff85511e40