[Controls] Fix style of options list button

[Heenawter]

Closes #161464

Summary

This PR fixes the styling of the options list control:

Before	After

Checklist

• This was checked for cross-browser compatibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[ThomThomson]

LGTM! Code only review. Do we know why this css wasn't needed before?

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 3e7f9bb

Failed CI Steps

• Security Solution Tests #3
• Explore - Security Solution Tests #2

Test Failures

• [job] [logs] Security Solution Tests #3 / Entity Analytics Dashboard With anomalies data enables a job
• [job] [logs] Explore - Security Solution Tests #2 / risk tab should be able to change items count per page

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
controls	199.8KB	199.9KB	+120.0B

Unknown metric groups

ESLint disabled line counts

id	before	after	diff
enterpriseSearch	14	16	+2
securitySolution	408	412	+4
total			+6

Total ESLint disabled count

id	before	after	diff
enterpriseSearch	15	17	+2
securitySolution	487	491	+4
total			+6

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @Heenawter

[andreadelrio]

LGTM! Code only review. Do we know why this css wasn't needed before?

The EUI team is currently investigating this. Seems like it has to do with an underlying component (EuiButtonEmpty) being converted to Emotion and EuiFilterButton not having been converted yet. They'll be working on a fix. Tagging them so they can provide a timeline @elastic/eui-team

[1Copenut]

EUI findings

Cee Chen and I took a look. Root cause theory is the order of Sass vs. Emotion css coming in, causing a style override. We are opting to move EuiFilterButton into Emotion and fold that into Kibana. I've got this on deck for Monday's grooming session. elastic/eui#6920

EUI CSS stacking order

Kibana CSS stacking order