[Enterprise Search] Fix EuiPageTemplate child usages

[cee-chen]

👋 Hey y'all ent search folks! I missed this fix/update update in our latest EUI upgrade (#182023). It's directly related to this change in EUI v94.2.0:

• Fixed an EuiPageTemplate bug where prop updates would not cascade down to child sections (#7648)
  • To cascade props down to the sidebar, EuiPageTemplate now explicitly requires using the EuiPageTemplate.Sidebar rather than EuiPageSidebar

In general, it's also a best practice to use EuiPageTemplate's namespaced children instead of the direct EuiPage* components (which are meant for direct usage within aEuiPage component instead), so I've made similar changes to your code as well. I would suggest pulling down this PR to QA that your page still looks as expected/as before.

[cee-chen]

/ci

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: e89e8c1

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
enterpriseSearch	2.7MB	2.7MB	-44.0B

History

• 💚 Build #208207 succeeded 8e469fd

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

[saarikabhasi]

Thank you @cee-chen for taking care of this.
I did smoke tests of all affected pages and I see changes in side nav in personal dashboard view. Adding a screen recording & screenshot of how current UI will look different with this change:
before

Screen.Recording.2024-05-08.at.10.23.19.PM.mov

after

Screen.Recording.2024-05-08.at.10.22.46.PM.mov

Not found page
before

after

Overall, I think now layout looks much better 🎉

[cee-chen]

Whew! Thanks for checking that and apologies for mildly breaking your layouts in the first place! 🙈