Add support to skip user ssh keys migrationMaster

Overview

add support to skip user ssh keys migration from BBS to GitLab

Update

Expanding flag to allow skipping all user keys migration:

• GL SSH & GPG keys
• BBS SSH keys

Closes #966 (closed)

Tasks

• Update docs if needed (workflow, runbooks, README, migration metrics, etc.)

Acceptance Criteria

• Existing UTs pass locally