feat(stovepipe): include request ID in build runner Trigger metadata

[mnoah1]

Summary

Intent:

• Add request ID to build metadata
• Build runner can use this to make it easier for the user to associate the build with its original request.
• Current use case: post a buildkite banner with the request ID and other build details.w

Changes:

• Define a stable optional BuildMetadata key for the Stovepipe request ID.
• Pass the request ID from the build controller when triggering full and incremental builds.

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Test Plan

• Pull this change in internally, include value in outbound annotation request for buildkite builds.

Issues

T3-CODEM-511