[DS] Change a different way to get all subId

Bug 28667616

This is a cherry-pick from https://partner-android-review.googlesource.com/#/c/219847.
It wasn't a "clean" merge because the multi-sim apis changed quite a bit
since the original CL.

Change-Id: Ib4a446e8753784c1a34765a80feefd9aa828be76