Fixes

• DB Update incorrectly appears on fresh installs. [#3390](https://github.com/wordimpress/give/issues/3390)
• Ensure the level title in the exported CSV reads custom on custom donations. [#3380](https://github.com/wordimpress/give/issues/3380)
• Don't allow db updates to display if AJAX is inaccessible. [#3393](https://github.com/WordImpress/Give/issues/3393)