Revamp database setup guides

The database setup guides could use some TLC. The pressing need here is that each specific setup guide needs instructions on how to set up a DB backup strategy, as we're really pushing external db strategies even more than before.

In addition:

• Sybase instructions should be removed; it's not supported
• Creating Database Schema Manually is an FAQ
• Known Issues For Supported Databases should be migrated to the KB. Where appropriate, necessary up-front configurations should be integrated straight into the setup guides
• The setup guides should get a standard look and feel.
  • DB setup on Oracle is JNDI only
  • DB setup on Postgres has screenshots, everything else doesn't, and it's Windows only
• Database Setup Guides is an unnecessary placeholder
• Database Setup for Oracle (Pre Confluence 2.2) should be deprecated (deleted)
• Database JDBC drivers should be integrated into the main setup docs (Have tidied up the page, and cross-linked to relevant content. There's some value in listing the status of the db drivers on one page.)
• Troubleshooting External Database Connections - move to KB (Have tidied up the page, and moved relevant content to KB.)
• Troubleshooting the Embedded Database (hSQL DB) - move to KB (Have tidied up the page, and moved relevant content to KB.)
• Upgrading From HSQL 1.7.1 to 1.8 should be deprecated