Update Security merger to handle security client
What does this MR do?
Update Security merger to handle security client
With the security development happening on GitLab.com, we need to merge security merge requests from different remotes, Security and Dev. To help with this Security::MergeRequestsMerger was modified to accept different security clients.
Other modifications included:
- Security merge task was modified to execute Merger with DevClient and Client if security_remote is enabled. If it's not enabled, then it's onlyl executed with dev client
- Fix typo on MergeRequestsValidator param comment
- Adjusts Merger specs
Related to https://gitlab.com/gitlab-org/release-tools/issues/344
Edited by Mayra Cabrera