Fix writing system we use in tests
Fix writing system we use in tests

When doing the data migration from 7000069 to 7000070 the
abbreviation field for the English writing system gets changed
from "en" to "Eng" although the abbreviations in other ws don't
get changed. This change makes the same change in our mongo
test double so that we don't introduce an extra hg commit which
our tests don't expect.

"Eng" matches what is in the global writing system store
(/var/lib/fieldworks/SIL/WritingSystemStore/en.ldml) - at least
on my machine :-).

ermshiperete/LfMerge,sillsdev/LfMerge,sillsdev/LfMerge,ermshiperete/LfMerge,sillsdev/LfMerge,ermshiperete/LfMerge