db: Make db:State self-healing on invalid connection (timeouts)

[zach2good]

I affirm:

• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

connection->reconnect() seemingly doesn't work. But ->isValid() wraps mysql_ping, so it's a good indicator of if the connection is going to work or not. We now rebuild the connection completely if isValid() fails.

[zach2good]

Tested by stripping out the ping job that was in there so that it doesn't try to reconnect and pings every 5s. Then restarting my MariaDB service repeatedly and see the new logging for "rebuilding connection" instead of the pings failing because ->reconnect() doesn't do what it promises