MSP-9653
Calling `ActiveRecord::Base.establish_connection`, followed by
`ActiveRecord::Base.connected?` returns false unless some other code
requires a connection to be checked out first. The correct way to check
if the spec passed to `ActiveRecord::Base.establish_connection` is to
checkout a connection and then ask if it is active.
`Msf::DBManager#connection_established?` does the checkout, active check
and checkin, and should be used in place of
`ActiveRecord::Base.connected?` and
`ActiveRecord::Base.connection_pool.connected?`.
`Msf::DBManager#active` should still be used as it also checks for
adapter/driver usability and that migrations have run.
Luke Imhoff
21fad7163d