fix: remove obsolete landlord profile indexes migration

backend/migrations/20260717-landlord-profile-indexes.js

@@ -1,9 +0,0 @@
-db.getSiblingDB('lmnp').landlords.createIndex(
-  { oidcSubject: 1 },
-  { name: 'landlords_oidc_subject_unique', unique: true, sparse: true },
-);
-
-db.getSiblingDB('lmnp').landlords.createIndex(
-  { email: 1 },
-  { name: 'landlords_email_unique', unique: true, sparse: true },
-);