Add rake task for process_security_target_issues

What does this MR do and why?

We added a security issue processor service that unlinks and links issues to a security release tracking issue that are ready to be included in an upcoming security release.

This MR adds a rake task to run that service and adds configuration so that task can be run from chatops. A separate MR will be opened on the chatops project to add the command once this change is merged.

While we will eventually run the processor service using a pipeline schedule, we still want the ability for release managers to run it on command, so that is why we are adding it to chatops.

Related to gitlab-com/gl-infra/delivery#19572 (closed)

Testing

I bypassed the content of TargetIssuesProcessor so we could just test the rake task itself:

diff --git a/lib/release_tools/security/target_issues_processor.rb b/lib/release_tools/security/target_issues_processor.rb
index 246b17c7..1835d246 100644
--- a/lib/release_tools/security/target_issues_processor.rb
+++ b/lib/release_tools/security/target_issues_processor.rb
@@ -7,6 +7,8 @@ module ReleaseTools
       TRACKING_ISSUE_PROJECT = 'gitlab-org/gitlab'

       def execute
+        puts 'done'
+        return true
         if security_target_issues.empty?
           logger.info("No target issues found, skipping.")

~/workspace/gitlab-org/release-tools (delivery19572-chatops-processor ✔) bundle exec rake security:process_security_target_issues
done

Author Check-list

• Has documentation been updated?