Merged some with_connections that were next to each other
merger -- one test error that I commented out because it depended on a connection being set
sanitization -- no testing errors
preloader/association -- no testing errors
associations/join_dependency -- no testing errors, but I feel that it should not work because it's going into another object
migration -- no testing errors
associations/has_many_through_association -- no testing errors
locking/optimistic -- no testing errors
relation/finder_methods -- no testing errors
uniqueness -- no testing errors
connection_handling -- no testing errors, Also added #with_connection which is a wrapper function for connection_pool.with_connection
explain -- no testing errors