Serialize json.extra.raw_response to avoid field explosion in logs

What does this MR do?

We're working on reducing the number of fields being logged as part of https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/10173.

Previous MRs in this series:

• !31910 (merged)
• !32583 (merged)

In this case we're indexing a lot of fields under json.extra.raw_response. By serializing that value, we'll save on 134 fields which account for ~25% of the current schema.

The consequence is that we won't be able to perform searches on individual values. We shouldn't need that though. The main use case is to find a specific error and then look up the full response that occurred.

Screenshots

Here's a flamegraph:

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team