Fix panel slices title not updated when locale changed

When calling getSliceData from SliceDataConverter, we were returning
the old version of List<SliceData> if there's one already existed.
So when the Locale get changed and we are re-indexing data, we
are still inserting the old List<SliceData> in database.  We should
reconstruct the List of SliceData instead of reusing the old
version here, since we only call SliceDataConverter#getSliceData
when we need to reindex.

Test: Manual verification
Fixes: 126732022
Change-Id: I42a3cf93dc313efefe50a34faabac9e1d616ef6c