Fix maximum call stack error for large combobox option groups

[chandlerprall]

Summary

Fixes an issue that has come up twice in Kibana support. The issue is that the spread operation,

matchingOptions.push(...matchingOptionsForGroup);

was transpiled to

matchingOptions.push.apply(matchingOptions, matchingOptionsForGroup);

which overflowed the call stack size when matchingOptionsForGroup array was too large (see https://mathiasbynens.be/demo/javascript-argument-count). The fix is to use the concat method to merge the two arrays. Also had to update a second instance in matching_options.ts with the same change.

Checklist

- [ ] Checked 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 any docs examples
• Added or updated jest and cypress tests
• Checked for breaking changes and labeled appropriately
  - [ ] Checked for accessibility including keyboard-only and screenreader modes
  - [ ] Updated the Figma library counterpart
• A changelog entry exists and is marked appropriately

[cee-chen]

Looks good to me! And also TIL :)

Super appreciate the inline comment as well as the unit test for regression! 🎉

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_5976/

[thompsongl]

Good find!