fix(model): drop leftover prefill_groups unique constraints before AutoMigrate (#7100)

model/main.go

@@ -321,6 +321,9 @@ func migrateDB() error {
 	if err := migrateTokenModelLimitsToText(); err != nil {
 		return err
 	}
+	if err := migratePrefillGroupUniqueIndex(DB); err != nil {
+		return err
+	}
 
 	err := DB.AutoMigrate(
 		&Channel{},
@@ -381,6 +384,9 @@ func migrateDB() error {
 }
 
 func migrateDBFast() error {
+	if err := migratePrefillGroupUniqueIndex(DB); err != nil {
+		return err
+	}
 
 	var wg sync.WaitGroup