[Dashboard] Fix missing state on short URL alias match redirect (#163658)

Fixes an issue where URL state from short URLs could be lost on an alias match redirect.

src/plugins/dashboard/public/dashboard_container/embeddable/create/create_dashboard.test.ts

@@ -51,7 +51,7 @@ test('throws error when provided validation function returns invalid', async ()
   }).rejects.toThrow('Dashboard failed saved object result validation');
 });
 
-test('returns undefined when provided validation function returns redireted', async () => {
+test('returns undefined when provided validation function returns redirected', async () => {
   const creationOptions: DashboardCreationOptions = {
     validateLoadedSavedObject: jest.fn().mockImplementation(() => 'redirected'),
   };
@@ -59,6 +59,24 @@ test('returns undefined when provided validation function returns redireted', as
   expect(dashboard).toBeUndefined();
 });
 
+/**
+ * Because the getInitialInput function may have side effects, we only want to call it once we are certain that the
+ * the loaded saved object passes validation.
+ *
+ * This is especially relevant in the Dashboard App case where calling the getInitialInput function removes the _a
+ * param from the URL. In alais match situations this caused a bug where the state from the URL wasn't properly applied
+ * after the redirect.
+ */
+test('does not get initial input when provided validation function returns redirected', async () => {
+  const creationOptions: DashboardCreationOptions = {
+    validateLoadedSavedObject: jest.fn().mockImplementation(() => 'redirected'),
+    getInitialInput: jest.fn(),
+  };
+  const dashboard = await createDashboard(creationOptions, 0, 'test-id');
+  expect(dashboard).toBeUndefined();
+  expect(creationOptions.getInitialInput).not.toHaveBeenCalled();
+});
+
 test('pulls state from dashboard saved object when given a saved object id', async () => {
   pluginServices.getServices().dashboardContentManagement.loadDashboardState = jest
     .fn()

src/plugins/dashboard/public/dashboard_container/embeddable/create/create_dashboard.ts

@@ -137,7 +137,6 @@ export const initializeDashboard = async ({
     useUnifiedSearchIntegration,
     useSessionStorageIntegration,
   } = creationOptions ?? {};
-  const overrideInput = getInitialInput?.();
 
   // --------------------------------------------------------------------------------------
   // Run validation.
@@ -161,6 +160,7 @@ export const initializeDashboard = async ({
   // --------------------------------------------------------------------------------------
   // Combine input from saved object, session storage, & passed input to create initial input.
   // --------------------------------------------------------------------------------------
+  const overrideInput = getInitialInput?.();
   const initialInput: DashboardContainerInput = cloneDeep({
     ...DEFAULT_DASHBOARD_INPUT,
     ...(loadDashboardReturn?.dashboardInput ?? {}),