Prevent datagrid cells from queuing up focus ownership

[chandlerprall]

Summary

Fixes #4975

A few things came together to create this bug:

• EuiDataGrid owns which cell is focused
• EuiDataGridCell subscribes to notifications about its focus state and responds accordingly by accepting focus
• EuiDataGridCell also reacts to it receiving focus by e.g. a user clicking on it, it tells the parent grid about the updated focus state in a setTimeout which is meant to allow any focus traps to deactivate before the cell re-claims focus
• If multiple cells receive focus within that same setTimeout delay, they each queued up the focus claim
• As the focus queue was processed, each cell noticed it was no longer focused and would re-queue its claim

This fix avoids any queuing by merging the timeouts into one.

Checklist

- [ ] Check against all themes for compatibility in both light and dark modes
- [ ] Checked in mobile

• Checked in Chrome, Safari, Edge, and Firefox
  - [ ] Props have proper autodocs and playground toggles
  - [ ] Added documentation
  - [ ] Checked Code Sandbox works for the any docs examples
  - [ ] Added or updated jest tests
• Checked for breaking changes and labeled appropriately
  - [ ] Checked for accessibility including keyboard-only and screenreader modes
• A changelog entry exists and is marked appropriately

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4983/

[snide]

Did a functional test of this and it solves the problems @andrew-goldstein and I noticed.

[thompsongl]

LGTM; tested with docs preview.
EUI cheat codes restored 👾