fix(ui5-dynamic-page-title): correct ARIA attribute handling for non-interactive titles (#12598)

When the DynamicPageTitle is non-interactive, the ARIA labelledby attribute
should not reference any heading elements. This change ensures that the
_ariaLabelledBy getter returns undefined when the title is not interactive,
preventing potential accessibility issues.

Fixes: #12466

Author: kgogov

packages/fiori/src/DynamicPageTitle.ts

@@ -276,6 +276,10 @@ class DynamicPageTitle extends UI5Element {
 	}
 
 	get _ariaLabelledBy() {
+		if (!this.interactive) {
+			return undefined;
+		}
+
 		const hasAnyHeading = this[this.headingSlotName].length;
 		if (hasAnyHeading) {
 			return `${this._id}-heading`;