[8.15] Cleanup aiAssistantFlyoutMode feature flag (#182992)

[kibanamachine]

Backport

This will backport the following commits from main to 8.15:

• Cleanup aiAssistantFlyoutMode feature flag (#182992)

Questions ?

Please refer to the Backport tool documentation

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: e4562b6

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
integrationAssistant	543	537	-6
securitySolution	5613	5606	-7
total			-13

Async chunks

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

id	before	after	diff
securitySolution	16.4MB	16.3MB	-144.8KB

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
securitySolution	86.5KB	86.5KB	-33.0B

Unknown metric groups

async chunk count

id	before	after	diff
securitySolution	101	99	-2

ESLint disabled in files

id	before	after	diff
@kbn/elastic-assistant	2	1	-1

ESLint disabled line counts

id	before	after	diff
@kbn/elastic-assistant	19	16	-3
securitySolution	550	549	-1
total			-4

Total ESLint disabled count

id	before	after	diff
@kbn/elastic-assistant	21	17	-4
securitySolution	633	632	-1
total			-5

History

• 💛 Build #220367 was flaky 619f8e7

cc @patrykkopycinski