Add MR metrics to clickhouse

Lohit Peesapatirequested to merge
lp-add-mr-data-to-clickhouse into main

Adds support for ingesting merge request webhook events into ClickHouse, enabling MR metrics tracking alongside existing pipeline, build, and issue metrics.

What does this MR do?

  1. Adds merge_request_metrics ClickHouse table schema with fields for MR state, branches, assignees, reviewers, labels, and merge details
  2. Implements MergeRequestEvent transformer to convert webhook payloads to ClickHouse format
  3. Extends webhook controller to process merge_request events (actions: open, close, reopen, update, merge)
  4. Adds recurring job to export MR data every 5 minutes
  5. Stores MR data in work_item_metrics database (same as issues)

Relates to https://gitlab.com/gitlab-org/quality/analytics/team/-/work_items/411

Edited by Lohit Peesapati

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