Warn customers to disable health checks when installing or migrating to DC

Issue Summary

Confluence has a few existing bugs (all duplicates of each other) where the installer or data center migration will break when a load balancer or proxy is pinging the server during the setup process:

• CONFSERVER-61188 - Opening the base URL multiple times during installation will break the installation process
• CONFSERVER-61189 - Opening the base URL multiple times during Data Center migration will break the migration process
• CONFSERVER-59084 - Improve installation process by preventing any other request to brake installation.

Customers will not know to do this prior to upgrading and will have to roll back and contact support if they have a health check in place.

Documentation Change Suggestion

We should add warnings to disable health checks and link to one of the bugs in the following documentation for all versions:

• Installing Confluence Data Center
• Installing Confluence on Windows
• Installing Confluence on Linux
• Installing Confluence on Windows from Zip File
• Installing Confluence on Linux from Archive File
• Migrate from Server to Data Center