fix(accordion): adding rti for keyboard navigation, removed internal navigation

[brianferry]

What I did

1. Remove the accordion specific keyboard navigation
2. Add the RTI (Roving Tab Index) controller to accordion after the accordion is initialized
3. This will fix the arrow up / arrow down issues related to [bug] <rh-accordion> Accessibility: arrow keys inside nested accordions don't work as expected RedHat-UX/red-hat-design-system#971

Testing Instructions

1. Go to DP demo page
2. Tab down to the accordion with nested accordions
3. Validate that the instructions located at RedHat-UX/red-hat-design-system#971 work here

Copied below for clarity

Steps to reproduce

- Run accordion demo locally
- Find nested example
- Expand first accordion item
- Tab inside to the child accordion
- Hit the down arrow (assuming it should go to the next item in the child accordion)
- Focus jumps to the parent accordion header

[changeset-bot]

🦋 Changeset detected

Latest commit: 130cb5c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@patternfly/pfe-core	Patch
@patternfly/elements	Patch

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