ref(sveltekit): Improve manual setup code snippets and structure

[Lms24]

builds on top of #10990

DESCRIBE YOUR PR

This PR adds a couple of improvements to the manual setup page of our SvelteKit guide:

• streamlined code snippets so that there's only one snippet per file users need to change. Since we can now highlight parts in snippets, I think it's easier for users to identify what they need to change in a file on one glance instead of piecing together two or three snippets.
• Removed TS and JS tabs in the snippets because there's no TS-specific syntax in them.
• Restructured H2 document structure so that not all optional configuration sections are part of "Configuration". This should help users identify what they have to do vs. what's optional and probably not necessary to read.

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PRE-MERGE CHECKLIST

Make sure you've checked the following before merging your changes:

• Checked Vercel preview for correctness, including links
• PR was reviewed and approved by any necessary SMEs (subject matter experts)
• PR was reviewed and approved by a member of the Sentry docs team

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
changelog	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Aug 9, 2024 11:39am
sentry-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Aug 9, 2024 11:39am

1 Skipped Deployment

Name	Status	Preview	Comments	Updated (UTC)
develop-docs	⬜️ Ignored (Inspect)	Visit Preview		Aug 9, 2024 11:39am

[codecov]

Bundle Report

Changes will decrease total bundle size by 15 bytes ⬇️

Bundle name	Size	Change
sentry-docs-server	8.26MB	6 bytes ⬇️
sentry-docs-edge-server	254.16kB	3 bytes ⬇️
sentry-docs-client	6.25MB	6 bytes ⬇️

[nicohrubec]

nice!