UpdateHeadPipelineForMergeRequestWorker should belong to Code Review

The following discussion from !34042 (merged) should be addressed:

@fabiopitino started a discussion:

TODO: open a follow-up issue to change this to worker to code_review

UpdateHeadPipelineForMergeRequestWorker currently has continuous_integration feature category but it should be code_review.

Edited Jul 23, 2021 by Fabio Pitino