Re-add troubleshooting guide for legacy source map upload

[lforst]

Aims to fix #7105

This PR re-adds troubleshooting docs that were removed in #7049 to streamline docs around sourcemaps for debug IDs.

What I didn't consider back then was that some platforms can't use debug IDs and still need some troubleshooting guide for the legacy process.

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Name	Status	Preview	Comments	Updated (UTC)
sentry-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 12, 2023 11:18am

[shanamatthews]

Hmm, I know we're already nested many levels deep, but what would you think about putting the legacy troubleshooting content in a sub-page?

[lforst]

Hmm, I know we're already nested many levels deep, but what would you think about putting the legacy troubleshooting content in a sub-page?

@shanamatthews I thought about it but the nesting felt weird. I generally don't like it when "folders" in the side bar have a lot of content, and we do that like 3 times in the source maps flow already.

The nesting would be source maps > troubleshooting > legacy upload > troubleshooting which I don't find optimal.

The whole docs situation around source maps docs sucks so much right now but I don't know how to do it properly. It's like every solution has a giant drawback 😢