refactor(material/dialog): updates prioritization order of aria-label adoption

Updates to put aria-labelledby values as the priority and the aria-label as
the backup.

Author: essjay05

src/material/dialog/dialog-container.ts

@@ -134,8 +134,7 @@ export class MatDialogContainer
       // If no ariaLabelledBy or ariaLabel, create default aria label
       !dialogNameElement && !this._config.ariaLabel
         ? 'Dialog Modal'
-        : // : Otherwise prioritize use of ariaLabel
-          this._config.ariaLabel || dialogNameElement?.innerText || dialogNameElement?.ariaLabel;
+        : dialogNameElement?.innerText || dialogNameElement?.ariaLabel || this._config.ariaLabel;
     return dialogNameInnerText || 'Dialog Modal';
   };