fix(popover): render arrow above backdrop (#28986)

Issue number: resolves #28985

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When a popover is being rendered in iOS mode, the arrow renders under
the backdrop.

![Screenshot 2024-02-06 at 11 59
58 AM](https://github.com/ionic-team/ionic-framework/assets/13530427/b55f8868-4de3-4f52-8e79-650a40f8d5bd)

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- The arrow renders at the same level as the content.

![Screenshot 2024-02-06 at 11 59
51 AM](https://github.com/ionic-team/ionic-framework/assets/13530427/05c214ee-6ba7-4cad-b00e-9668dca23f73)

- [ ] Yes
- [x] No

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Credit [Sahil-B07](https://github.com/Sahil-B07) for providing the
[fix](https://github.com/ionic-team/ionic-framework/pull/28430). A new
PR had to be created in order to update snapshots.

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Co-authored-by: Sahil Bhor <92709590+Sahil-B07@users.noreply.github.com>
Co-authored-by: ionitron <hi@ionicframework.com>

core/src/components/popover/popover.ios.scss

@@ -35,6 +35,13 @@
   height: 10px;
 
   overflow: hidden;
+  /*
+   * Required for the arrow to render above the backdrop.
+   * Otherwise, the arrow will appear slightly transparent.
+   * The value is set to 11 since it's the minimum value that
+   * will allow the arrow to render above the backdrop.
+   */
+  z-index: 11;
 }
 
 .popover-arrow::after {