Update post-deploy migration related to approval project rules

What does this MR do and why?

Update post-deploy migration in order to only delete vulnerability rules instead of triggering sidekick job.

Related issue: #362553 (closed)

Database:

Migrate

== 20220517144749 RemoveVulnerabilityApprovalRules: migrating =================
== 20220517144749 RemoveVulnerabilityApprovalRules: migrated (0.0089s) ========

Rollback

== 20220517144749 RemoveVulnerabilityApprovalRules: reverting =================
== 20220517144749 RemoveVulnerabilityApprovalRules: reverted (0.0000s) ========

Query

DELETE FROM 
  "approval_project_rules" 
WHERE 
  "approval_project_rules"."report_type" = 1;

Query plan

https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/10148/commands/35814

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.