since login command create a new session, we run into an
issue when describe was called after login
seem like the row_factory wasn't used

the reason was in the main session we used `execution_profiles`
while in the one create in login we did not, which led to copying
the wrong values (i.e. like `row_factory` that was needed for server
side describe)

this change saves the profiles into the instance, and reuse them
when ever a new session is opened
it simplify the code and we could remove a few repetitions of
the same logic