test: [M3-8890] - Fix flaky DBaaS resize test related to recent factory changes (#11238)

* Set DBaaS resize test mock database instance platform to `'rdbms-legacy'`

* Added changeset: Fix DBaaS resize tests that fail on first attempt and succeed on second

Author: jdamore-linode

packages/manager/.changeset/pr-11238-tests-1731115121832.md

@@ -0,0 +1,5 @@
+---
+"@linode/manager": Tests
+---
+
+Fix DBaaS resize tests that fail on first attempt and succeed on second ([#11238](https://github.com/linode/manager/pull/11238))

packages/manager/cypress/e2e/core/databases/resize-database.spec.ts

@@ -50,7 +50,7 @@ const resizeDatabase = (initialLabel: string) => {
 describe('Resizing existing clusters', () => {
   databaseConfigurationsResize.forEach(
     (configuration: databaseClusterConfiguration) => {
-      describe(`Resizes a ${configuration.linodeType} ${configuration.engine} v${configuration.version}.x ${configuration.clusterSize}-node cluster`, () => {
+      describe(`Resizes a ${configuration.linodeType} ${configuration.engine} v${configuration.version}.x ${configuration.clusterSize}-node cluster (legacy DBaaS)`, () => {
         /*
          * - Tests active database resize UI flows using mocked data.
          * - Confirms that users can resize an existing database.
@@ -70,6 +70,7 @@ describe('Resizing existing clusters', () => {
             cluster_size: 3,
             status: 'active',
             allow_list: [allowedIp],
+            platform: 'rdbms-legacy',
           });
 
           // Mock account to ensure 'Managed Databases' capability.