[Guided Onboarding] Make onboarding panel auto height

[cindychangy]

Fixes issue #144334

Making the panel not take the full height of the screen as is the default of EuiFlyout which we are using.

Notes:

• Realized when reading the docs, that there is a maxWidth prop for the EuiFlyout so I swapped that with the custom style we had
• Revised the custom styles in panel_styles.ts to achieve this
• I put a max-height on the panel so there is always room for 1 toast

Let me know if you think there is a better way to approach this.

[elasticmachine]

Pinging @elastic/platform-onboarding (Team:Journey/Onboarding)

[yuliacech]

nit: would it be possible to delete the property completely?

[alisonelizabeth]

(If it's not possible to delete, it might be worth adding a comment to explain why.)

[cindychangy]

@yuliacech @alisonelizabeth - good point, I added a comment to clarify (does not work if we remove these values) - I had one quick question, is this placement the correct place to put it, or should I add it all the way at the top with the commented description:

/**
 *
 * Style overrides for the setup guide dropdown panel.
 * There is currently no existing EUI component that fully supports what we need...

[alisonelizabeth]

I think this is OK 👍. Not sure if there are any specific guidelines around this, but in this case, I think it's easier to follow next to the CSS.

[yuliacech]

same here, maybe we could delete height?

[yuliacech]

Thanks a lot, @cindychangy! LGTM, left a couple of nits in the comments.

[alisonelizabeth]

Verified locally. LGTM. Thanks @cindychangy!

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: ad4e0fd

Metrics [docs]

Page load bundle

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

id	before	after	diff
guidedOnboarding	20.8KB	20.8KB	+29.0B

Unknown metric groups

ESLint disabled in files

id	before	after	diff
osquery	1	2	+1

ESLint disabled line counts

id	before	after	diff
enterpriseSearch	19	21	+2
fleet	60	66	+6
osquery	109	115	+6
securitySolution	445	451	+6
total			+20

Total ESLint disabled count

id	before	after	diff
enterpriseSearch	20	22	+2
fleet	69	75	+6
osquery	110	117	+7
securitySolution	521	527	+6
total			+21

History

• 💚 Build #93937 succeeded a824bfc

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