Take advantage of db default

Author: aarongable

sa/db-next/boulder_sa/20250519000000_NullRegistrationsContact.sql

@@ -0,0 +1 @@
+../../db/boulder_sa/20250519000000_NullRegistrationsContact.sql

sa/db-next/boulder_sa/20250519000000_NullRegistrationsContact.sql

@@ -0,0 +1,9 @@
+-- +migrate Up
+-- SQL in section 'Up' is executed when this migration is applied
+
+ALTER TABLE `registrations` ALTER COLUMN `contact` SET DEFAULT '[]';
+
+-- +migrate Down
+-- SQL section 'Down' is executed when this migration is rolled back
+
+ALTER TABLE `registrations` ALTER COLUMN `LockCol` DROP DEFAULT;

sa/db/boulder_sa/20250519000000_NullRegistrationsContact.sql

@@ -276,9 +276,6 @@ type regModel struct {
 	CreatedAt time.Time `db:"createdAt"`
 	LockCol   int64
 	Status    string `db:"status"`
-	// Deprecated: never populated from the database, and always written to the
-	// database as just "[]".
-	Contact string `db:"contact"`
 }
 
 func registrationPbToModel(reg *corepb.Registration) (*regModel, error) {
@@ -304,7 +301,6 @@ func registrationPbToModel(reg *corepb.Registration) (*regModel, error) {
 		ID:        reg.Id,
 		Key:       reg.Key,
 		KeySHA256: sha,
-		Contact:   "[]",
 		Agreement: reg.Agreement,
 		CreatedAt: createdAt,
 		Status:    reg.Status,