GRO-298: Batch client insert and UAT test client insert both used
schema.clients.email as the ON CONFLICT target, but clients.email has
no unique constraint in the schema, causing the seed to crash with:
PostgresError: there is no unique or exclusion constraint matching
the ON CONFLICT specification
Both calls now use schema.clients.id (the primary key) as the target,
and include email in the set clause since we're no longer updating on
email match.
Co-Authored-By: Paperclip <noreply@paperclip.ing>