refactor(): update directories to use kebab case (#27230)

Issue number: N/A

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

The team decided on some new processes for adding tests. One of those
processes is that test directories should use kebab case.

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

- Updates test directories to use kebab case

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->


## Other information

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

core/src/components/loading/test/is-open/loading.e2e.ts

@@ -5,7 +5,7 @@ test.describe('loading: isOpen', () => {
   test.beforeEach(async ({ page, skip }) => {
     skip.rtl('isOpen does not behave differently in RTL');
     skip.mode('md', 'isOpen does not behave differently in MD');
-    await page.goto('/src/components/loading/test/isOpen');
+    await page.goto('/src/components/loading/test/is-open');
   });
 
   test('should open the loading indicator', async ({ page }) => {