fix(cdk-experimental/accordion): removes inert attribute from accordion trigger (#31817)

Updates accordion trigger attributes by removing the inert
attribute to allow for screen readers to reference the
aria-labelledby id value of the trigger when associating
it with the accordion content panel.

Fixes b/438312273

fix(cdk-experimental/accordion): removes inert attribute from accordion trigger

Removes the inert attribute from accordion trigger to enable screen
readers to access the accordion trigger id and aria attributes to be
able to announce more helpful/informative screen reader messages to the
user.

Fixes b/438312273

Author: essjay05

src/cdk-experimental/accordion/accordion.ts

@@ -93,7 +93,6 @@ export class CdkAccordionPanel {
     '[attr.aria-expanded]': 'pattern.expanded()',
     '[attr.aria-controls]': 'pattern.controls()',
     '[attr.aria-disabled]': 'pattern.disabled()',
-    '[attr.inert]': 'hardDisabled() ? true : null',
     '[attr.disabled]': 'hardDisabled() ? true : null',
     '[attr.tabindex]': 'pattern.tabindex()',
     '(keydown)': 'pattern.onKeydown($event)',