[Console] Run console test on chrome only

[alisonelizabeth]

Related to #157776

This PR updates the Console variables test to only run on Chrome. In May, our CI workers were updated with a new Firefox browser version, which caused some tests to be slower and flaky. The QA team does not have a working solution yet, so the current strategy is to disable flaky Firefox tests and run on Chrome instead. See #158405 for more context.

[alisonelizabeth]

@elasticmachine merge upstream

[alisonelizabeth]

Ran tests 100x, see: https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/2486. There was one failure, but it was related to a separate Console test.

[elasticmachine]

Pinging @elastic/platform-deployment-management (Team:Deployment Management)

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 5da3d2b

Metrics [docs]

Unknown metric groups

ESLint disabled line counts

id	before	after	diff
enterpriseSearch	14	16	+2
securitySolution	413	417	+4
total			+6

Total ESLint disabled count

id	before	after	diff
enterpriseSearch	15	17	+2
securitySolution	492	496	+4
total			+6

History

• 💚 Build #138317 succeeded dbb4afc
• 💔 Build #137843 failed 8cb7b35
• 💚 Build #137819 succeeded 944a1b4

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