Revert "fixing import of marginalia into inactive connection adapters".  it was problematic because it causes ActiveRecord to actually make the connection to the database - straight away when the gem loads, before any other gems etc. have had a chance to hook the database connection class.  the commit message doesn't explain why this was done, but I suspect it's because not all connection adapters have the same methods present to alias - but that will be fixed in subsequent commits.

This reverts commit 43c93e2aca4deff72fc72ef7c64a751da162ec9b.