Update Defend page's metadata to change to Protect
Issue Description
Several pages in the docs that currently have the stage name of Defend
in their metadata need to be changed to Protect
for the stage name, to help outside contributors more effectively connect with us.
- https://docs.gitlab.com/ee/topics/web_application_firewall/index.html
- https://docs.gitlab.com/ee/topics/web_application_firewall/quick_start_guide.html
- https://docs.gitlab.com/ee/user/application_security/container_scanning/index.html
- https://docs.gitlab.com/ee/user/application_security/threat_monitoring/index.html
- https://docs.gitlab.com/ee/user/project/clusters/securing.html