chore(formatting): undo shared formatter and keep structuredcontent

[shayna-ch]

removes everything related to the sentry shared formatter, no real behavioral change since the flag was turned off in the Sentry side so the shared formatter wasn't used. get_issue_details still returns structuredContent, now built from the MCP's own data.

deleted:

• The ?llmFormat=json / ?llmFormat=markdown params on the event and autofix requests.
• The formatted field on the event and autofix schemas.
• usesSharedFormatterBody and wrapSeerContent, and the code that used them in get_issue_details, analyze_issue_with_seer and formatIssueOutput.

structuredContent:

• event.body is now the MCP's own markdown for the event (formatEventOutput), not a parsed formatter payload. Transactions get the structured path too, with their performance trace in the body.
• New event.message and responseNotes fields, so the structured result carries everything the markdown output shows. The markdown output and the structured payload build their notes with the same function.
• Will only be on for users opted in to experimental mode. Outside experimental mode it will fallback to the og markdown

[shayna-ch]

bugbot run

[cursor]

✅ Bugbot reviewed your changes and found no new issues!

Comment @cursor review or bugbot run to trigger another review on this PR

^{Reviewed by Cursor Bugbot for commit a9ba625. Configure here.}