This takes the loading time from 14s to 13s

Use a o3tl::sorted_vector to reduce searching time

Change-Id: I947a3e5001fe1058cf9bffc9509d026af4122ef4
Reviewed-on: https://gerrit.libreoffice.org/71035
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>