[Dashboard] Fix Title BWC (#95355) (#95446)

* allow saving blank string to panel title

src/plugins/dashboard/common/embeddable/embeddable_saved_object_converters.ts

@@ -29,17 +29,14 @@ export function convertPanelStateToSavedDashboardPanel(
   panelState: DashboardPanelState,
   version: string
 ): SavedDashboardPanel {
-  const customTitle: string | undefined = panelState.explicitInput.title
-    ? (panelState.explicitInput.title as string)
-    : undefined;
   const savedObjectId = (panelState.explicitInput as SavedObjectEmbeddableInput).savedObjectId;
   return {
     version,
     type: panelState.type,
     gridData: panelState.gridData,
     panelIndex: panelState.explicitInput.id,
     embeddableConfig: omit(panelState.explicitInput, ['id', 'savedObjectId', 'title']),
-    ...(customTitle && { title: customTitle }),
+    ...(panelState.explicitInput.title !== undefined && { title: panelState.explicitInput.title }),
     ...(savedObjectId !== undefined && { id: savedObjectId }),
   };
 }