Change error tracking collector status code

What does this MR do and why?

Changes response code for collector from 204 to 200.

Because some SDK expect code to be 200 otherwise they consider request a failure 💆

Example of SDK checking for 200 are:

• https://github.com/getsentry/sentry-dotnet/blob/317d4ad7905c605eaad4c416137fee35fb9ea68f/src/Sentry/Internal/Http/HttpTransport.cs#L160
• https://github.com/getsentry/sentry-java/blob/b45944c93d53f68bc1e64f5ac4c9a5400b252d44/sentry/src/main/java/io/sentry/transport/HttpConnection.java#L273

For #343531 (closed)

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