fix: prevent live-sample render errors killing the whole build

[LeoMcA]

See: #9154

Not entirely sure what the underlying issue is here: with playground, our routing logic for localised cross document live samples must have changed, and now we can't find some. Rather than debugging and fixing that, I'm letting them remain broken, but preventing them from killing the entire build.

An example of a file which fails is yarn build files/fr/learn/forms/how_to_structure_a_web_form/index.md like so:

Error: From URL /fr/docs/Web/Guide/HTML/Formulaires/Comment_structurer_un_formulaire_HTML/Exemple no folder on disk could be found. Tried to find a folder called fr/web/guide/html/formulaires/comment_structurer_un_formulaire_html/exemple
    at render (file:///workspace/yari/kumascript/index.ts:65:11)
    at Element.<anonymous> (file:///workspace/yari/kumascript/src/live-sample.ts:104:29)
    at LoadedCheerio.map (file:///workspace/yari/node_modules/cheerio/lib/esm/api/api/traversing.ts:618:20)
    at Module.buildLiveSamplePages (file:///workspace/yari/kumascript/src/live-sample.ts:93:8)
    at buildDocument (file:///workspace/yari/build/index.ts:241:44)
    at async buildDocumentInteractive (file:///workspace/yari/build/cli.ts:76:29)
    at async buildDocuments (file:///workspace/yari/build/cli.ts:169:20)
    at async Se._action (file:///workspace/yari/build/cli.ts:465:60)
    at async Se.run (/workspace/yari/node_modules/@caporal/core/dist/index.js:1:27579)
    at async Te._run (/workspace/yari/node_modules/@caporal/core/dist/index.js:1:32257)

When building all documents, this would error out the entire build for that locale. For some reason we don't catch this in our action and error out the entire action - instead we seem to plod on, only uploading the documents which managed to be built prior to that error.

In summary, this:

• catches the errors, lets the build proceed

On monday we should debug and fix:

• what's changed with the routing of embedlivesample
• why our action didn't fail

[LeoMcA]

Stage build succeeded: https://github.com/mdn/yari/actions/runs/5364125550/jobs/9732120691

Self approval