Deleting git repository with many MPs times out

OOPS-37cfede9eefb5b51adcbbef4f1a1b738 shows lots of missing bulk operations. The top ones are:

1. 188 572 3 569 SQL-main-master
DELETE
FROM BranchMergeProposalJob
WHERE BranchMergeProposalJob.id = $INT

2. 65 528 8 520 SQL-main-master
SELECT $INT
FROM (
SELECT GitRepository.default_branch,
       GitRepository.date_created,
       GitRepository.date_last_modified,
       GitRepository.description,
       GitRepository.distribution,
       GitRepository.id,
       GitRepository.information_type,
       GitRepository.name,
       GitRepository.owner_default,
       GitRepository.OWNER, GitRepository.project,
                            GitRepository.registrant,
                            GitRepository.repository_type,
                            GitRepository.reviewer,
                            GitRepository.sourcepackagename,
                            GitRepository.target_default
FROM GitRepository
WHERE GitRepository.id IN ($INT)
  AND (GitRepository.information_type IN ($INT, $INT)
  OR COALESCE((GitRepository.access_grants)&&
    (SELECT ARRAY_AGG(TeamParticipation.team)
     FROM TeamParticipation
     WHERE TeamParticipation.person = $INT), FALSE)
  OR COALESCE(ARRAY[(GitRepository.access_policy)]&&
                (SELECT ARRAY_AGG(AccessPolicyGrant.policy)
                 FROM AccessPolicyGrant
                 JOIN TeamParticipation ON TeamParticipation.team = AccessPolicyGrant.grantee
                 WHERE TeamParticipation.person = $INT), FALSE)) LIMIT $INT) AS "_tmp" LIMIT $INT

3. 62 375 6 369 SQL-main-master
DELETE
FROM CodeReviewMessage
WHERE CodeReviewMessage.id = $INT

4. 33 130 3 127 SQL-main-master
DELETE
FROM CodeReviewVote
WHERE CodeReviewVote.id = $INT

5. 32 160 5 155 SQL-main-master
SELECT BranchMergeProposal.commit_message,
       BranchMergeProposal.date_created,
       BranchMergeProposal.date_merged,
       BranchMergeProposal.date_review_requested,
       BranchMergeProposal.date_reviewed,
       BranchMergeProposal.description,
       BranchMergeProposal.id,
       BranchMergeProposal.merge_reporter,
       BranchMergeProposal.merged_revision_id,
       BranchMergeProposal.merged_revno,
       BranchMergeProposal.dependent_branch,
       BranchMergeProposal.dependent_git_commit_sha1,
       BranchMergeProposal.dependent_git_path,
       BranchMergeProposal.dependent_git_repository,
       BranchMergeProposal.queue_status,
       BranchMergeProposal.registrant,
       BranchMergeProposal.reviewed_revision_id,
       BranchMergeProposal.reviewer,
       BranchMergeProposal.root_message_id,
       BranchMergeProposal.source_branch,
       BranchMergeProposal.source_git_commit_sha1,
       BranchMergeProposal.source_git_path,
       BranchMergeProposal.source_git_repository,
       BranchMergeProposal.superseded_by,
       BranchMergeProposal.target_branch,
       BranchMergeProposal.target_git_commit_sha1,
       BranchMergeProposal.target_git_path,
       BranchMergeProposal.target_git_repository,
       BranchMergeProposal.whiteboard
FROM BranchMergeProposal
WHERE BranchMergeProposal.superseded_by = $INT
ORDER BY BranchMergeProposal.date_created DESC, BranchMergeProposal.id

6. 32 151 4 147 SQL-main-master
SELECT CodeReviewVote.branch_merge_proposal,
       CodeReviewVote.vote_message,
       CodeReviewVote.date_created,
       CodeReviewVote.id,
       CodeReviewVote.registrant,
       CodeReviewVote.review_type,
       CodeReviewVote.reviewer
FROM CodeReviewVote
WHERE CodeReviewVote.branch_merge_proposal = $INT

7. 32 91 2 89 SQL-nostore
SELECT Webhook.active,
       Webhook.branch,
       Webhook.date_created,
       Webhook.date_last_modified,
       Webhook.delivery_url,
       Webhook.git_repository,
       Webhook.id,
       Webhook.json_data,
       Webhook.registrant,
       Webhook.secret,
       Webhook.snap
FROM Webhook
WHERE Webhook.git_repository = $INT
ORDER BY Webhook.id

8. 31 456 14 442 SQL-main-master
SELECT BranchMergeProposalJob.json_data,
       BranchMergeProposalJob.branch_merge_proposal,
       BranchMergeProposalJob.id,
       BranchMergeProposalJob.job,
       BranchMergeProposalJob.job_type
FROM BranchMergeProposalJob
WHERE BranchMergeProposalJob.branch_merge_proposal = $INT

9. 31 207 6 201 SQL-main-master
SELECT CodeReviewMessage.branch_merge_proposal,
       CodeReviewMessage.id,
       CodeReviewMessage.message,
       CodeReviewMessage.vote,
       CodeReviewMessage.vote_tag
FROM CodeReviewMessage
WHERE CodeReviewMessage.branch_merge_proposal = $INT

10. 31 161 5 156 SQL-main-master
DELETE
FROM BranchMergeProposal
WHERE BranchMergeProposal.id = $INT

11. 31 121 3 118 SQL-main-master
DELETE
FROM PreviewDiff
WHERE PreviewDiff.branch_merge_proposal = $INT

12. 10 26 2 24 SQL-main-master
DELETE
FROM CodeReviewInlineComment
WHERE CodeReviewInlineComment.previewdiff IN ($INT)

13. 10 25 2 23 SQL-main-master
DELETE
FROM CodeReviewInlineCommentDraft
WHERE CodeReviewInlineCommentDraft.previewdiff IN ($INT)