Rename index for sqlite support

SQLite requires unique index names across the full database.  A previous
patch I9b6468221ba6fe501b15c563f3301694262eec65 renamed the index in
echo.sql but forgot to apply the same change to existing databases. This
resolves that mistake.

Change-Id: Ibb629149afd9f4ca55cac613124fce42500aa8f9