Fix broken double quote escaping in alert templates

Double quotes have to be escaped manually before being inserted into the panes query, so " or %22 becomes \" or %5C%22. This is because unfortunately if a query parameter has a JSON value Grafana will only accept it if it uses double quotes, not single quotes.

This issue that was causing some alert links not to work.

As part of: gitlab-com/gl-infra/scalability#3622 (closed)