Variables: Prevents enter key from refreshing page or changing focus (#39666)

public/app/features/variables/textbox/TextBoxVariablePicker.tsx

@@ -46,6 +46,7 @@ export function TextBoxVariablePicker({ variable, onVariableChange }: Props): Re
   const onBlur = (e: FocusEvent<HTMLInputElement>) => updateVariable();
   const onKeyDown = (event: KeyboardEvent<HTMLInputElement>) => {
     if (event.keyCode === 13) {
+      event.preventDefault();
       updateVariable();
     }
   };