fix(alert): remove border-right on ios stacked buttons (#28821)

Issue number: internal

---------

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issue. -->

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## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

When iOS alert has 3 or more buttons, those are rendered vertically. All
but the last button will have a right border. There shouldn't be a right
border when the buttons are stacked.

![Group
2(1)](https://github.com/ionic-team/ionic-framework/assets/13530427/0bc2a46e-554c-459a-85cb-990f4b4918ed)


## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- Vertical buttons don't have a right border.
- Separated the test in order to also test dark theme.

![Screenshot 2024-01-12 at 1 00
54 PM](https://github.com/ionic-team/ionic-framework/assets/13530427/5ec9d00f-2893-4045-9b63-2817549c80b1)
![Screenshot 2024-01-12 at 12 58
22 PM](https://github.com/ionic-team/ionic-framework/assets/13530427/5b64a959-b8e1-4b6a-bd9c-92d1d381a65a)


## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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below.
  2. Update the BREAKING.md file with the breaking change.
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## Other information

<!-- Any other information that is important to this PR such as
screenshots of how the component looks before and after the change. -->

N/A

---------

Co-authored-by: ionitron <hi@ionicframework.com>

core/src/components/alert/alert.ios.scss

@@ -265,6 +265,22 @@
   flex-wrap: $alert-ios-button-group-flex-wrap;
 }
 
+/**
+  * The right border should only be applied to the first button
+  * when the group has 2 or less buttons (horizontal).
+  * Otherwise, the right border should not be applied
+  * when the group has 3 or more buttons (vertical).
+  */
+.alert-button-group-vertical .alert-button {
+  border-right: none;
+
+  &:last-child {
+    @include rtl() {
+      border-right: none;
+    }
+  }
+}
+
 .alert-button {
   /**
    * This padding ensures that alerts

core/src/components/alert/test/basic/alert.e2e.ts

@@ -73,11 +73,6 @@ configs().forEach(({ config, screenshot, title }) => {
       await alertFixture.screenshot('longMessage');
     });
 
-    test('more than two buttons', async () => {
-      await alertFixture.open('#multipleButtons');
-      await alertFixture.screenshot('multipleButtons');
-    });
-
     test('no message', async () => {
       await alertFixture.open('#noMessage');
       await alertFixture.screenshot('noMessage');
@@ -105,6 +100,41 @@ configs().forEach(({ config, screenshot, title }) => {
   });
 });
 
+configs({ themes: ['light', 'dark'] }).forEach(({ config, screenshot, title }) => {
+  test.describe(title('should not have visual regressions'), () => {
+    test('more than two buttons', async ({ page }) => {
+      await page.setContent(
+        `
+        <ion-alert
+          header="Alert"
+          sub-header="Subtitle"
+          message="This is an alert message."
+          is-open="true"
+        ></ion-alert>
+
+        <script>
+          const alert = document.querySelector('ion-alert');
+          alert.buttons = [
+            'Open Modal',
+            {
+              text: 'Delete',
+              id: 'delete-button',
+              role: 'destructive',
+            },
+            'Cancel'
+          ];
+        </script>
+      `,
+        config
+      );
+
+      const alert = page.locator('ion-alert');
+
+      await expect(alert).toHaveScreenshot(screenshot(`alert-multipleButtons`));
+    });
+  });
+});
+
 class AlertFixture {
   readonly page: E2EPage;
   readonly screenshotFn?: (file: string) => string;