[FIX: #39152] Public links refer to `null` when question is new (#39154)

...s/sharing/public-sharing-embed-button-behavior.cy.spec.js

.../scenarios/visualizations-tabular/pivot_tables.cy.spec.js

.../dashboard/components/DashboardEmbedHeaderButton/index.ts

...etabase/dashboard/components/EmbedMenu/AdminEmbedMenu.tsx

...shboard/components/EmbedMenu/AdminEmbedMenu.unit.spec.tsx

...base/dashboard/components/EmbedMenu/NonAdminEmbedMenu.tsx

...ic/components/ResourceEmbedButton/ResourceEmbedButton.tsx

...nts/ResourceEmbedButton/ResourceEmbedButton.unit.spec.tsx

...c/metabase/public/components/ResourceEmbedButton/index.ts

...end/src/metabase/query_builder/components/QueryModals.tsx

...src/metabase/query_builder/components/view/ViewFooter.jsx