test(styles): update button styles for test pages (#29931)

Issue number: internal

---------

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## What is the current behavior?
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Test styles causes native buttons to have [certain
styling](https://github.com/ionic-team/ionic-framework/blob/main/core/scripts/testing/styles.css#L52-L64).
This was done to spruce up the buttons used for testing purposes only.
However, this ended up adding styles to native buttons within Ionic
components.

## What is the new behavior?
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this PR. -->

- Test styles for native buttons are only applied to buttons that are
not part of a Ionic component

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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screenshots of how the component looks before and after the change. -->

How to test:

1. Run the project locally from the `main` branch
2.
[Comment](5d208e9daa/core/src/components/searchbar/searchbar.md.scss (L91))
out `border: 0` from `.searchbar-clear-button` from the searchbar `md`
theme file (`ios` also works)
3. Navigate to the basic test page:
`/src/components/searchbar/test/basic`
4. Notice a teal border around the clear buttons
5. Checkout to this PR's branch
6. Make sure steps 2-3 are done
7. Verify that the teal border is not being applied to the clear buttons
8. Verify that only native buttons outside of the Ionic components have
a teal appearance: `/src/components/loading/test/standalone` and
`/src/components/action-sheet/test/is-open`

core/scripts/testing/styles.css

@@ -49,8 +49,19 @@ html.ios.ios {
   font-family: -apple-system, BlinkMacSystemFont, "iosTestingFont", sans-serif;
 }
 
-ion-content button,
-main button {
+/**
+ * Button styles should only be applied
+ * to native buttons that are not part of the
+ * Ionic framework.
+ * Otherwise, the styles may not appear correctly
+ * when comparing between testing and production.
+ * This issue occurs only with `scoped` components,
+ * which is why `sc-ion-` is used as a filter,
+ * since this class is specifically added to `scoped`
+ * components.
+ */
+ion-content button:not([class*="sc-ion-"]),
+main button:not([class*="sc-ion-"]) {
   display: inline-block;
   width: auto;
   clear: both;
@@ -63,8 +74,19 @@ main button {
   margin: 8px 0;
 }
 
-ion-content button.expand,
-main button.expand {
+/**
+ * Button styles should only be applied
+ * to native buttons that are not part of the
+ * Ionic framework.
+ * Otherwise, the styles may not appear correctly
+ * when comparing between testing and production.
+ * This issue occurs only with `scoped` components,
+ * which is why `sc-ion-` is used as a filter,
+ * since this class is specifically added to `scoped`
+ * components.
+ */
+ion-content button.expand:not([class*="sc-ion-"]),
+main button.expand:not([class*="sc-ion-"]) {
   display: block;
   width: 100%;
 }