test(many): replace ionic buttons in e2e tests with native html buttons (#29422)

Issue number: internal

---------

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## What is the current behavior?
The `ion-button` component is used in several tests to navigate or show
overlays. This causes screenshot diffs in unrelated tests any time the
UI of the `ion-button` is updated.

## What is the new behavior?
Removes the `ion-button` elements from unrelated tests. 

Did not remove the `ion-button`s from the following tests:
- All `ion-button`s in an `ion-buttons` component
- An `ion-button` inside of a menu
- breadcrumbs/test/basic (uses a clear button in a list header, needs to
be moved)
- input/test/slot
- item/test/buttons
- item/test/colors
- item/test/dividers
- item/test/inputs
- item/test/media
- list-header/test/basic
- ripple-effect/test/basic
- router/test/basic
- router/test/guards
- router-outlet/test/basic
- select/test/slot
- textarea/test/slot

Updates the icon/basic test to use the right icon names by comparing
against the v3 names: https://ionicframework.com/docs/v3/ionicons/

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

---------

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

core/src/components/tabs/test/basic/index.html

@@ -16,6 +16,18 @@
       :root {
         --ion-safe-area-bottom: 40px;
       }
+
+      .custom-white {
+        --background: white;
+        --background-hover: #888;
+        --background-focused: #444;
+
+        --color: #3880ff;
+      }
+
+      .ios .custom-white {
+        --background-activated: #ddd;
+      }
     </style>
   </head>
 
@@ -30,8 +42,8 @@
           </ion-header>
           <ion-content class="ion-padding">
             <h1>Tab One</h1>
-            <ion-button expand="block" onclick="updateBadgeCount()">Update Badge Count</ion-button>
-            <ion-button color="secondary" expand="block" onclick="updateBadgeColor()">Update Badge Color</ion-button>
+            <button class="expand" onclick="updateBadgeCount()">Update Badge Count</button>
+            <button class="expand" onclick="updateBadgeColor()">Update Badge Color</button>
 
             <ion-fab slot="fixed" horizontal="end" vertical="bottom">
               <ion-fab-button class="custom-white">
@@ -124,19 +136,5 @@
       }
       customElements.define('page-one', PageOne);
     </script>
-
-    <style>
-      .custom-white {
-        --background: white;
-        --background-hover: #888;
-        --background-focused: #444;
-
-        --color: #3880ff;
-      }
-
-      .ios .custom-white {
-        --background-activated: #ddd;
-      }
-    </style>
   </body>
 </html>