During a migration, the destination share instance export location
was being shown, thus the user could get confused as to which
export location to choose when mounting his share, since only
the source could be mounted.
This patch addresses this by filtering the destination
export location out.
APIImpact
Change-Id: I20cf1a76399693d751fa87fc4df375162e7c5f1d
Closes-bug: #1660726