[Embeddable] Register ML embeddables synchronously

[cqliu1]

Summary

Cherry-picked c528ca0 from #215947.

This registers the ML embeddable synchronously to avoid a racing condition where the dashboard could try to render an ML embeddable before the embeddable is available.

Checklist

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• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
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[elasticmachine]

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

[nreese]

Looks like registerEmbeddables is getting called twice. You will need to remove the second call on line 299

[cqliu1]

Looks like registerEmbeddables is getting called twice. You will need to remove the second call on line 299

Good catch! Fixed in 76e76c4

[nreese]

LGTM
code review only

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: ec61ffe

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
ml	4.5MB	4.5MB	+31.7KB

Page load bundle

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

id	before	after	diff
ml	77.0KB	77.6KB	+660.0B

Unknown metric groups

async chunk count

id	before	after	diff
ml	112	115	+3

[pmuellr]

So this wasn't backported? And won't be available in 8.19, 9.0, or 9.1? Is it not needed in those branches? We have someone expecting the fix, who upgraded from an older 8.18 to 9.1.2, and are still having this problem ...

[nreese]

So this wasn't backported? And won't be available in 8.19, 9.0, or 9.1? Is it not needed in those branches? We have someone expecting the fix, who upgraded from an older 8.18 to 9.1.2, and are still having this problem ...

This PR merged the fix into 8.18. This fix was merged into 8.19 and 9.1 in a much larger PR that could not be backported to 8.18. If you look at x-pack/platform/plugins/shared/ml/public/plugin.ts in 8.19 and 9.1, those branches have this fix applied.

8.19 branch has fixes https://github.com/elastic/kibana/blob/8.19/x-pack/platform/plugins/shared/ml/public/plugin.ts#L276
9.1 branch has fixes https://github.com/elastic/kibana/blob/9.1/x-pack/platform/plugins/shared/ml/public/plugin.ts#L287

Looks like 9.0 is the only branch missing the fix.

Maybe this is a new issue and we should open a different issue?