Remove admin_level=8 from the admin_city_names index
Remove admin_level=8 from the admin_city_names index

As we no longer restrict rendering to administrative boundaries of
level 8, rework the index for city name lookups.

NOTE: if you have an existing PostGIS database, you will need to
recreate the index. First, remove the existing one with:
`DROP INDEX admin_city_names` then re-create it with the
`CREATE INDEX ...` statement from ocitysmap-init.sql.

Signed-off-by: Maxime Petazzoni <76f7aeeb2d6ed04ef2b101cc81e4baac9b89c3cf@bulix.org>

dittaeva/ocitysmap,maposmatic/ocitysmap,ccnz/eqnz-ocitysmap,dittaeva/ocitysmap,maposmatic/ocitysmap,maposmatic/ocitysmap