[Security solution] Fix streaming on cloud

[stephmilovic]

Summary

Unfortunately, the strategy to use a TransformStream in the invokeStream method (see 1, 2) was unsuccessful in production. The transform caused additional latency and caused the stream not to work at all when passing through the cloud proxy. I removed the TransformStream from the stack_connectors, and instead we need to count on the consumer to properly parse the response stream.

Bedrock

Bedrock will sometimes send multiple messages in one buffer. To account for this, I again followed the langchain bedrock extension and used a concatenated buffer to process multiple messages one at a time.

To test

1. Test with the deployment on this PR
2. Use vault to access creds: vault read secret/kibana-issues/dev/cloud-deploy/kibana-pr-171578
3. Ensure Knowledge Base is turned off
4. Test with both OpenAI and Bedrock credentials, responses should stream
5. Test stop generating and regenerate buttons
6. I also created connectors with bad model. Test that you receive an error with the connectors labeled "bad model"

[stephmilovic]

@elasticmachine merge upstream

[elasticmachine]

Pinging @elastic/security-threat-hunting (Team:Threat Hunting)

[elasticmachine]

Pinging @elastic/security-solution (Team: SecuritySolution)

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 7385c6b
• Cloud Deployment

Failed CI Steps

• Serverless Investigations - Security Solution Cypress Tests #1

Test Failures

• [job] [logs] Serverless Investigations - Security Solution Cypress Tests #1 / Correlation tab should update timeline after removing eql should update timeline after removing eql

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
securitySolution	4706	4733	+27

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
securitySolution	12.8MB	12.8MB	+19.2KB

History

• 💔 Build #178213 failed 9d13e54
• 💔 Build #178190 failed b89ef7f
• 💔 Build #178154 failed 6995899
• 💔 Build #178134 failed 555ccc8
• 💔 Build #177756 failed 781d3d6

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[semd]

LGTM