Migrate and cleanup legacy scss

[kertal]

Summary

Cleanup and migrate legacy scss of src/legacy/ui/public/styles/_legacy/

• Deletes unused CSS
• Moves single plugin CSS usage to the consuming plugin
• Migrated base layout css to src/core/public/styles

Fixes #69135

[kertal]

@elasticmachine merge upstream

[kertal]

@elasticmachine merge upstream

[kertal]

I'm getting an error in Timelion trying to start this up to test it. Looks to be a bad .scss import in src/plugins/timelion/public/directives/_index.scss with the saved_object_finder import.

@crob611 thx, yes, didn't work, fixed it, and due to changes, the canvas team review is no longer required. but of course you could have a look, that everything is fine :)

[kertal]

The main thing I'm concerned about here is that the application styles that determine the layout of the whole page (and some chrome styles) are now under the "legacy" style import but really I think all applications need it, even they do override it

@kertal If there are base styles used by everything, I think it's fair moving them into core. @joshdover do you think that's the right approach here? I guess it's mostly about this stuff: #69369 (files)

@joshdover @flash1293 So for now, should I move them to e.g. src/legacy/ui/public/styles/_base.scss? until you move them to src/core/public/styles?

I have no problem with you moving these directly into src/core/public/styles, but we can also manage moving them in #58369 if that is easier.

@joshdover I've migrated those style to src/core/public/styles

[cchaos]

Ahhh, that feels better. Thanks! Just one comment about a duplicate file but otherwise LGTM

[flash1293]

Tested in Firefox, focusing on Timelion, Discover and data table vis. Didn't notice any breakages, LGTM.

Thanks for this PR, this is one of the very last Kibana app legacy platform parts 💯 🥇

[kertal]

@elasticmachine merge upstream

[kertal]

@elasticmachine merge upstream

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 7ff95d4

Build metrics

@kbn/optimizer bundle module count

id	value	diff	baseline
kibanaLegacy	95	+9	86

async chunks size

id	value	diff	baseline
discover	431.2KB	+2.9KB	428.3KB
home	510.5KB	-356.0B	510.9KB
kibanaLegacy	147.1KB	-6.0KB	153.1KB
security	1.1MB	-712.0B	1.1MB
spaces	45.6KB	-356.0B	45.9KB
timelion	591.1KB	+8.7KB	582.3KB
total	-	+4.2KB	-

page load bundle size

id	value	diff	baseline
core	1.1MB	-95.5KB	1.2MB
kibanaLegacy	246.8KB	+14.2KB	232.6KB
ml	4.3MB	-4.5KB	4.3MB
visTypeTable	604.6KB	+184.0B	604.4KB
total	-	-85.7KB	-

History

• 💚 Build #62555 succeeded 94a738b
• 💛 Build #62262 was flaky 8ceb8be
• 💚 Build #62210 succeeded fe7368e
• 💔 Build #62184 failed 8bb8c90
• 💔 Build #62049 failed 1ac2518

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

[peteharverson]

ML edits LGTM