messageable user: fix bookmarked pagination

fixes CNVS-13547

test plan:
  * open Conversations as a user who can message many users
  * open compose dialog
  * open recipient browser
  * open a context with more than one page of recipients
  * scroll through all results
  * verify that all recipients are shown

Change-Id: Iaa043e98499b1f22520cbcd3d3c10dc404b9fb49
Reviewed-on: https://gerrit.instructure.com/36181
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jacob Fugal <jacob@instructure.com>
QA-Review: Steven Shepherd <sshepherd@instructure.com>
Product-Review: Braden Anderson <braden@instructure.com>